JP3329739B2 - Projection optics in the planetarium - 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 for projecting various patterns such as stars on a planetarium.

[0002]

2. Description of the Related Art In a planetarium, various patterns of an illuminated projection original plate (hereinafter, referred to as an original plate) are projected on a dome surface by a projection lens to reproduce a starry sky. The pattern of a star such as a star is represented by a transmission hole provided in the original plate.

[0003]

In this case, in order to reproduce the actual starry sky, the projected star image must be projected so as to be an apparent image, and the star which looks small will be accordingly. The transmission holes in the original plate must also be made small.

[0004] However, if the transmission hole of the original plate becomes small, the illumination light cannot be sufficiently introduced and the projection is hindered.
The minimum star image that can be projected is limited, and there is a problem that accurate starry sky cannot be reproduced.

On the other hand, when projecting a place where a large number of stars gather, an elaborate original plate must be created.
Processing technology and cost became problems. Further, in this case, when the stars are close to each other, the processing is difficult because the transmission holes representing the stars are close to each other.

Although the above problems can be solved by enlarging the original plate itself, the projection lens also becomes larger,
Not only has the projection optical system increased in size and the production cost increased, but also there has been a problem contrary to the recent demand for downsizing the planetarium projection device.

In this case, it is conceivable that a reduction optical system is arranged between the original plate and the projection lens. However, this time, the distance of the entire projection optical system is increased by the reduction optical system, and the manufacturing cost is increased by the complicated reduction optical system. In addition to the bulkiness, a problem has also arisen against the downsizing of the planetarium projection device.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a projection optical system which solves the above-mentioned problems of the prior art, and converges toward a projection lens in front of a projection original plate. By arranging a tapered optical fiber bundle, the reduced pattern of the original plate is displayed on the exit side end face of the optical fiber bundle, and this is projected.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, the "optical fiber bundle" is a well-known optical element comprising a group of many optical fibers having a fine diameter, and is also called an image guide, an image fiber, or a fiber optic plate. The optical fiber bundle has a structure in which an aggregate of fine-diameter fibers in which a high-refractive-index core glass (core portion) is coated with a low-refractive-index coating glass (cladding portion) is fused, and incident light is emitted into the fiber. The total reflection is repeated and the light is efficiently transmitted from the entrance surface to the exit surface with high resolution.In the entire optical fiber bundle, the image incident from one end is divided into pixels corresponding to the number of fibers and transmitted, and transmitted to the end surface on the exit side. It is displayed, and this end face itself can be regarded as a set of countless light emitters. As the optical fiber bundle, in addition to a straight type (face plate) from one end face to the other end face in which each optical fiber is kept in the same arrangement while maintaining a parallel state, one end face is diffused or converged in a radial manner. There is a tapered shape from the other end surface to the other end surface.

In the present invention, the pattern of the original plate which is incident from the incident end face of the tapered optical fiber bundle is transmitted to the exit end face, and a reduced image is displayed there. Projected onto the surface. In this case, it is possible to enlarge the size of the original plate itself to a reciprocal multiple of the reduction magnification with respect to the pattern displayed on the end face on the emission side of the optical fiber bundle.

[0011]

FIG. 1 is a view showing an embodiment of a projection optical system according to the present invention. Reference numeral 3 in the figure denotes a light source such as a light bulb. Light from this light source is condensed by a condenser lens 4 and passes through a transmission hole of the projection original plate 2 to obtain a transmission pattern.

A tapered optical fiber bundle 1 whose both ends are polished flat is closely or closely disposed in front of the projection original plate 2, and the transmission pattern of the original plate 2 is incident from the incident side end face 1A of the optical fiber bundle. The light is divided into pixels corresponding to the number of fibers, transmitted, and displayed on the end face 1B on the emission side. In this case, since the optical fiber bundle 1 is tapered so as to converge toward the projection lens side, the interval between the optical fibers, that is, the pixels, is reduced at the emission end face 1B, and the pattern displayed here is reduced. The reduced pattern is projected on the dome surface S by the projection lens 5.

FIG. 2 is a view for explaining the above-mentioned operation. Here, the pattern P1 (S1 is a transmission hole corresponding to a star) of the original plate 2 incident on the optical fiber bundle 1 is reduced at the end face on the emission side of the optical fiber bundle. Pattern P2 (S
2 is indicated as a transmission hole corresponding to a star).

In this embodiment, the optical fiber bundle 1 is arranged close to or close to the original plate 2.
When arranged close to each other, it is needless to say that means (for example, filling of a transparent substance) for transmitting the light beam into the optical fiber bundle without being diffused is required depending on the degree of proximity.

[0015]

The present invention having the above configuration has the following specific effects. Since the size of the original plate can be increased with respect to the pattern projected by the projection lens, sufficient illumination light can be introduced, and a brighter projected image can be obtained for the same pattern than in the related art.

The above is the case where the projected pattern is the same size as the prior art. However, even if the pattern is smaller than that of the prior art, a bright projected image equivalent to that of the prior art can be obtained. The range of the minimum star image expands.

Since the size of the original plate can be made larger than the pattern projected by the projection lens, a precise pattern can be realized at low cost, and a more accurate projected image can be obtained.

Since the original plate can be made larger than the pattern projected by the projection lens, a fine pattern can be realized even if a solid display element such as an LCD or an active image display device such as a CRT is used as the original plate. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a projection optical system according to the present invention.

FIG. 2 is a principle view showing an operation of the embodiment.

[Explanation of symbols]

 1 optical fiber bundle 2 original plate 5 projection lens

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidehiko Miyazaki 127-1, Nose, Shimoichi, Kushigata-cho, Nakakoma-gun, Yamanashi Prefecture Examiner, Koto Minami, Yamanashi Plant, Goto Optical Laboratory Co., Ltd. (56) References JP-A-62-191818 (JP) JP-A-9-281435 (JP, A) JP-A-8-271986 (JP, A) JP-B-47-17317 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB G03B 21/00 G09B 27/00

Claims (1)

(57) [Claims] An optical fiber bundle converging toward a projection lens is disposed in front of a projection original plate, so that a reduced pattern of the original plate is displayed on an end face of the optical fiber bundle on the emission side and projected. A projection optical system for a planetarium.