JPH0421172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a dome-shaped screen, that is, a spherical screen. More specifically, the present invention relates to a dome-shaped screen that is suitable for projecting images by a projector such as a projector or a projection television set inside the dome-shaped screen and being viewed by an audience at a viewing position provided at the bottom of the dome.

(b) Prior Art Dome-shaped screens are used as various exhibition halls such as planetariums, and are known for projecting images onto the screen and allowing the audience to view the images within the screen. There are two ways to project images onto a dome-shaped screen: installing a projector such as a projector or television inside the dome-shaped screen;
A method of projecting an image from behind a dome-shaped screen is known.

(C) Problems to be Solved by the Invention Unlike ordinary screens made of flat surfaces, dome-shaped screens have irregular reflections when images are projected from the center of the interior using a projector such as a movie projector or television. Light is projected onto other parts of the screen, creating so-called stray light. It is known that the stray light causes a problem in that the contrast of the screen image decreases. For this reason, attempts have been made to partially drill holes in the screen, but in that case, there was a problem in that the brightness of the projected image decreased.

On the other hand, the method of projecting images from outside the dome-shaped screen has the problem that the projection method of the projector is more complicated than that of internal projection.

(d) Means for Solving the Problems This invention provides a dome-shaped screen in which a projector is installed inside and a viewing position can be formed on the bottom of the dome, which is capable of reflecting the projected light from the projector and is capable of forming a viewing position on the bottom of the dome. A plurality of concave surfaces with a size smaller than the resolution of the eye are provided toward the inside of the dome, and the aperture of the concave surface allows the reflected light to be reflected only in the direction of the viewing position on the bottom of the dome, and not in the direction of other dome-shaped screens. These conventional problems are solved by providing a dome-shaped screen.

(e) Effect The projection light projected from the projector is reflected by multiple concave mirrors. The reflected light from each concave mirror is reflected only in the direction of the viewing position and is not directed toward the screen, so that no stray light occurs. Furthermore, the concave surfaces provided at the periphery of the dome-shaped screen have a shape that limits the luminous flux of reflected light on the dome-shaped screen center side to a greater extent than the concave surfaces provided near the center point of the dome-shaped screen. If the side of the screen is aligned with the dome surface, there will inevitably be a step between the bottom side and the dome surface, but if this surface is used as a light-shielding surface, even if light scattered by other screen surfaces reaches the concave mirror. Even if the light is exposed, this portion blocks light and prevents light from passing through. Furthermore, since each concave surface has a dimension that is below the resolution of the eye, the reflected light from each surface is perceived as a bright spot from the viewing position, and the collection of adjacent bright spots is perceived as a continuous, wide-area bright image.

(F) Embodiment 1 showing a central sectional view of the first embodiment of the present invention.
The explanation will be made with reference to FIG. 2, which is a central sectional view of the second embodiment.

The embodiment shown in FIG. 1 has a dome-shaped screen 1 and a viewing position 3 provided on a horizontal bottom surface 2.
On the other hand, in the embodiment shown in FIG. 2, the viewing position 3 is provided on the sloping bottom surface 2, as seen in recent planetarium theaters, and the seats are tilted forward. In both embodiments, the bottom surface 2 is circular, and a projector 4 such as a movie projector or a projection television is installed at the center point 0 of the bottom surface.
A large number of concave mirrors 5 are fixed to the inner surface of the spherical screen 1, with their reflective surfaces facing inside the dome. The size of the concave mirror 5 (concave reflective surface) is preferably smaller than the point of visual observation from each viewing position, and the size of the bottom surface 2 is 20 to 30 mm.
In the case of a spherical screen having a diameter of about 3 to 5 mm, each radius of the spherical screen is about 3 to 5 mm. The concave surface of each concave mirror 5 at point A in FIGS. 1 and 2 is a paraboloid of revolution as shown in FIG. 3 or a spherical surface as shown in FIG. 4. When a concave mirror is formed from a paraboloid of revolution as shown in FIG.
Since it is larger than the focal length of the concave mirror, it is considered to be a substantially parallel light, and when this parallel light is projected in the optical axis direction of the concave mirror 5, it is reflected by the mirror surface and then reflected by the concave mirror as shown in FIG. Focus the light on focal point F. Then focus F
Diffuses in the direction of a cone with the apex at . The direction in which this reflected light is diffused, that is, the direction of the bottom surface of the cone, is within the range of the bottom surface 2, preferably within the range where the eyes of the audience exist, or at least in the direction of the spherical screen 1. The curved surface has an aperture that prevents the reflected light from moving toward the spherical screen 1. When the concave mirror 5 is made of a spherical surface as shown in FIG. 4, spherical aberration occurs and the reflected light is diffused without focusing on the focal point. within the range of
That is, the spherical screen 1 has an aperture that does not allow reflected light to pass through, and is installed with the optical axis of the concave mirror facing the projector 4. In order to diffuse the reflected light in the two directions of the bottom surface, it is not desirable that all the concave surfaces 5 provided inside the spherical screen 1 have the same shape and that the reflected light is not processed, in which case stray light will occur.
That is, in the embodiment shown in FIG. 1, the zenith A (i.e., the center point A of the dome-shaped screen), and in the embodiment shown in FIG. At the center point A) of the dome-shaped screen, the concave surface 5 that sets the diffusion direction of reflected light within the bottom surface 2 is defined as ∠AOB=∠BOC=∠COD=
If the optical axis of the concave mirror 5 is oriented toward the projector 4, ∠B′BE,
The reflected light in the range of

Therefore, in the embodiment shown in FIGS. 1 and 2,
As shown in FIG. 5, the concave mirror 5 at point A has a curved surface that diffuses the projected light from the projector into the bottom surface 2, but at point B it has a curved surface as shown in FIG. 6, and at point C it has a curved surface as shown in FIG. In addition, the projector 4 has a concave shape that does not have a surface that reflects the projected light from the projector 4 outward in the two directions of the bottom surface, that is, toward the spherical dome, and a light shielding portion 6 is provided in the direction in which the reflected light travels outward in the two directions of the bottom surface.

That is, in each of the concave surfaces 5 shown in FIGS. 6 and 7, the curved surface forming the concave surface 5 is completed to the screen surface on the dome-shaped screen center point A side, but on the peripheral side, the curved surface forming the concave surface 5 is completed to the light shielding part 6. It is continuous and does not reach the screen surface as a continuous peripheral surface.
As shown in FIGS. 6 and 7, the optical axis of the curved surface of the concave mirror 5 is directed toward the projector 4, and the concave surface 5 provided around the dome-shaped screen 1 forms a curved bottom side portion of the dome. As shown in Figure 8 A to C, by making the opening from the center of the dome-shaped screen smaller toward the periphery, the concave surface fixed to the periphery of the dome-shaped screen reflects light upward. The shape has a large proportion of controlling the luminous flux.

The light-shielding portion 6 is formed by applying black coating that absorbs light, and absorbs the light reflected from the two concave mirrors toward the outside of the bottom surface. Since the angle of the projection light from the projector 4 is different at points B and C, the shape of the light shielding part and the shape of the concave surface are also changed. Theoretically, it is desirable to change the shape of the light shielding part 6 and the concave mirror 5 for each adjacent concave mirror 5 from point A to point D.

However, in the case of a concave mirror 5 with a bottom surface 2 of 20 to 30 m in length and a diameter of about 3 to 5 mm within 1 minute, points A to B, points B to C, and points C to D are concave mirrors of the same shape. Even if the light shielding part 6 is used, there is no difference in practical use. That is, points A and B have a shape shown in cross section in FIG. 5 and in plan view in FIG. 8A. Points B to C are located at an angle of 30° above the optical axis of BO, as shown in the cross section in Figure 6 and the plane in Figure 8B.
It has a shape that limits the luminous flux of reflected light.

Points C to D are shown in cross section in FIG. 7 and in plan in FIG.
Consists of shape. Depending on the shape of the concave mirror 5 and the shape of the light shielding part 6, the shape may be changed more finely.

In the embodiment shown in FIGS. 1 and 2, the surface of the spherical screen 1 is formed by consecutively forming a plurality of plate-shaped bodies 7 each consisting of a set of concave mirrors 5 and light shielding parts 6. The part between the concave mirrors 5 is formed by a light-shielding absorption part 8,
No reflected light is generated due to anti-reflection treatment. Furthermore,
In the plate-like body 7, as shown in FIGS. 9A, 9B, and 9C, there is no problem in practical use even if the light shielding portion 6 is linear in plan view. In this case, it is suitable for forming a concave surface with a smaller area. The light-shielding absorption portion 8 may be formed by printing.
The light-shielding and absorbing portion 8 includes the parts A, B, C and 10 in Fig. 9.
As shown in Figures A, B, and C, small holes for sound absorption may be provided. The small holes 9 make it possible to improve the acoustic effect. The seat on which the viewer is seated may be a so-called so-called sonic seat incorporating a sound device, in which case the sound effect will be further improved.

In the embodiment shown in FIGS. 13 and 14, the concave mirror 5
In some of the installation locations, concave mirrors 5 are not installed and holes 10 are provided for sound absorption.

In this case, the acoustic reflection caused by the dome is
0 absorbs sound, and although the brightness decreases somewhat, the sound absorption effect increases.

As shown in FIG. 11, the plate-like body 7 is made of a transparent material such as plastic, and is formed by making the inside of the dome smooth, and forming an uneven surface on the outside, which is then mirror-finished. Further, as shown in FIG. 12, the flat plate may be subjected to an uneven treatment, so that the inner surface of the dome may also be made into a spherical surface or a paraboloid of revolution.

(G) Effects Therefore, the present invention provides a dome-shaped screen that does not reduce contrast or brightness and does not generate stray light, and since the concave surface has a size smaller than the resolution, the reflected light from each surface is reduced. provides a dome-shaped screen that is perceived by the audience as a bright spot, and is perceived as a continuous, wide-area image by a collection of adjacent bright spots.

[Brief explanation of drawings]

FIG. 1 is a central sectional view of a first embodiment of the invention;
Fig. 2 is a central sectional view of the second embodiment, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9.
Figures, Figure 10, Figure 11, Figure 12, Figure 13,
FIG. 14 is a partially enlarged view of the embodiment. 1...Dome-shaped screen, 2...Bottom surface, 3...
...Viewing position, 4...Projector, 5...Concave mirror, 6...
...light-shielding part, 7... plate-like body, 8... light-shielding absorption part,
9...Small hole.

Claims (1)

[Claims] 1. In a dome-shaped screen where a projector is installed inside and a viewing position can be formed on the bottom of the dome, it is possible to reflect the projected light from the projector, and a concave mirror with a size smaller than the resolution of the eye is placed from the viewing position. , a plurality of concave mirrors are provided toward the inside of the dome, and the aperture of each concave mirror has a shape whose outer periphery is the intersection line of the concave surface and the extended surface of the cone formed by the condensing point and the bottom surface of the dome, or a shape close to it. None A dome-shaped screen characterized by no light rays being reflected in any direction other than the direction of the bottom of the dome.