JP2000039671A - Projection optical system in planetarium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bright projection picture with respect to an identical pattern by arranging a tapered optical fiber bundle converged toward a projection lens side in front of a projection original plate, displaying the pattern of the reduced original plate at the emitting-side end surface of the optical fiber bundle and projecting it. SOLUTION: The transmitted pattern is obtained by condensing light emitted from a light source 3 by a condenser lens 4 and passing it through the transmission hole of the projection original plate 2. The tapered optical fiber bundle 1 is arranged in front of the plate 2 so that it is closely brought into contact with the plate 2 or it is near to the plate 2. Then, the pattern transmitted through the plate 2 is made incident from the incident-side end surface 1A of the bundle 1, divided into pixels as many as the number of optical fibers, transmitted and displayed at the emitting-side end surface 1B. Since the bundle 1 is tapered so as to be converged toward the projection lens side, a gap between the optical fiber, that means, the gap between the pixels is reduced at the end surface 1B and the reduced pattern is projected on a dome surface S by a projection lens 5.

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 real starry sky, the projected star image must be projected so as to be an apparent image, and the star which looks small will be correspondingly. The transmission holes in the original plate must also be made small.

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

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

[0006] The above problems can be solved by enlarging the original plate itself.
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 the projection lens in front of the original projection plate. By arranging the tapered optical fiber bundle, the reduced pattern of the original plate is displayed on the end face on the emission side 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 a large number of 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. 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 is 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 the optical fibers are kept in the same position while maintaining a parallel state, one end face is diffused or converged in a radial manner. There is a tapered shape from the 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 by the reciprocal of the reduction ratio with respect to the pattern displayed on the end face on the emission side of the optical fiber bundle.

[0011]

FIG. 1 is a diagram showing an embodiment of a projection optical system according to the present invention. In the figure, reference numeral 3 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 and close to each other is 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. In this figure, 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 exit end face 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 a means (for example, filling of a transparent substance or the like) for transmitting the light beam into the optical fiber bundle without diffusing the light beam 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 a 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 increased with respect to 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 sophisticated pattern can be realized even when a solid display device 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 Mitsuru Omori 1247-1 Nose, Shimoichi, Kushigata-cho, Nakakoma-gun, Yamanashi Pref. 1 Inside the Goto Optical Research Laboratory Yamanashi Plant (72) Inventor Hidehiko Miyazaki 1247-1 Nose, Shimoichi, Kushigata-cho, Nakakoma-gun, Yamanashi Prefecture F-term in the Goto Optical Research Laboratory Yamanashi Plant F-reference (reference)

Claims (1)

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