JPH0545733A - Front screen - Google Patents

Abstract

PURPOSE:To obtain nearly maximum gain at the respective parts of a front screen viewed from the point of view even when the point of view and the position of a projector are distant right and left and up and down, to obtain a bright screen and to obtain a video having uniform lightness as the entire front screen by improving directivity from the front screen to the point of view. CONSTITUTION:Very minute aspherical concaves 6 are uniformly provided at very minute intervals as a whole on the surface of the front screen 2 where the video is made incident from the projector 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a front screen which is installed on a projection front surface of a video projection device such as a video projector for projecting a video and watches reflected light thereof.

[0002]

2. Description of the Related Art Conventionally, as a front screen for this type of video projector, a white mat made of white vinyl chloride or the like, a silver screen coated with aluminum powder, a pearl screen coated with pearl essence such as shells, and glass beads are used. There is a bead screen that is evenly scattered over the surface of the screen fabric.

The necessary conditions for displaying images on these front screens are: As a projection environment, even in places with a certain level of brightness,
A high gain that represents the light reflection performance for a bright image. 2. Angle of eyes (hereinafter referred to as viewing angle) with respect to the front screen at the place where the image is viewed (hereinafter referred to as viewpoint)
Therefore, the decrease in gain is small. Is raised.

The gain according to the viewing angle of each of the front screens described above varies depending on the manufacturer, but an example is shown below. White Silver Pearl Beads Matte Screen Screen Screen 0 ° 0.9 3.38 2.85 2.48 10 ° 0.88 2.7 2.4 1.76 20 ° 0.86 1.5 1.35 1.19 30 ° 0.84 0.78 0.84 0.91 40 ° 0.82 0.44 0.6 0.79

From the above numerical values, the silver screen has a high reflectance and the gain varies depending on the manufacturer, but it is as high as 3.38 at a viewing angle of 0 °, but is as low as 0.44 at a viewing angle of 40 °. Therefore, if the viewing angle deviates from the center of the screen, there is a drawback that the image suddenly darkens.

In order to improve this, the developed pearl screen has a gain of 2.85 at a viewing angle of 0 °, which is slightly lower than that of a silver screen, but maintains a gain of 0.6 at a position separated by 40 °. There is. Further, since the white mat diffuses and reflects the incident light in four directions, it has a gain of 0.9 at a viewing angle of 0 ° and a gain of 0.82 at a position of 40 °.
However, since the reflectance is low as described above, the image becomes dark no matter where it is viewed, and there is a drawback that it cannot be put to practical use unless it is in an extremely dark place.

Further, in order to eliminate these drawbacks, the bead screen adopts means such as mixing glass beads having different refractive indexes n, and the reflectance of light is reduced in spite of diffusing incident light in four directions. The gain is 2.48 at a viewing angle of 0 °, which is slightly inferior to the above-mentioned pearl screen, but is improved to 0.79 even at a position 40 ° apart.

Among these front screens, the white matte, silver screen and pearl screen are
As shown in FIG. 7, with respect to the incident light from the projector 1, the reflection is emitted with the angle α formed by the incident light and the vertical surface of the screen 2 as the main optical axis.

However, even in this case, since the screen surface is not a perfect mirror surface, the reflectance in each direction differs depending on the type of screen, and therefore, as shown in the previous table, even for angles deviated from the optical axis. Is spread at a high rate. On the other hand, in the bead screen, as shown in FIG. 8, the light incident on the glass beads 3 is reflected by the reflective film 4 provided on the spherical half surface, and the light as shown in FIG. 9 is returned to the incident side. It becomes sex.

The ratio of the dispersion of the light reflected by the reflective film in each direction changes depending on the refractive index of the light of the glass forming the glass beads 3, so that glass beads having different refractive indexes are to be obtained. Blend in the required proportions depending on the properties.

[0011]

However, in a front screen such as a silver screen or a pearl screen that reflects at the same angle β as the incident angle α from the projector 1, as is clear from the above table, the directivity is strong. However, the reflected light cannot be effectively directed toward the viewpoint 5, which makes it difficult to maintain uniform brightness of the entire image.

Further, in the bead screen, as shown in FIG. 9, when the projector 1 is hung from the ceiling and installed on an extension of a line orthogonal to the upper end of the front screen 2, the reproducibility is improved. However, the light returns to the projector 1 side, and it becomes difficult to collect the light at the viewpoint 5 to form a bright image.

In any of the methods, depending on the position of the viewpoint 5, no gain can be obtained at the end of the front screen 2 or the gain difference becomes severe, making it difficult to see the image. May occur.
On the other hand, since the darkness in the home cannot be darkened like in a theater, the contrast of the image must be increased as a front screen, and the front screen is required to have a high gain.

It is an object of the present invention to solve the above-mentioned drawbacks of the conventional front screen, and to provide a front screen in which the installation location of the projector is not specified and the whole is almost uniform and bright images can be obtained. And

[0015]

SUMMARY OF THE INVENTION The present invention has as its gist the means of a front screen for achieving the above-mentioned object, and it is uniform over the entire surface on the projection surface side from the projection device of the screen. The object is achieved by providing finely distributed fine aspherical concave surfaces.

Further, in this front screen, the projection surface side of the screen from the projector is divided into a plurality of divided surfaces, and each divided surface is evenly and finely distributed over the entire surface. And provided with a fine aspherical concave surface having a different curved surface, or the projection surface side of the screen from the projector, a rectangle where horizontal and vertical lines intersect,
A plurality of U-shaped surfaces surrounding the rectangle are provided, and each of the divided surfaces is a fine non-uniform surface uniformly and finely distributed over the entire surface. It is more desirable to provide a spherical concave surface.

[0017]

In the front screen of the present invention, by providing a fine aspherical concave surface on the surface of the front screen on which the image is projected, the reflection direction of the incident light is directed to the viewpoint direction, and the gain at the viewpoint is obtained. To obtain a bright image.

Further, the surface of the front screen on which the image is projected is a plurality of divided surfaces,
By changing the curved surface of the aspherical concave surface provided on each surface, the reflection direction of the incident light on each surface is directed to the viewpoint direction, and the gain on each divided surface is increased.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIGS.
Will be described. In FIG. 1, 1 is a projector, 2 is a front screen that receives a projection from the projector 1 and projects an image, and 5 is a viewpoint from which the image is viewed.

On the incident surface side of the image from the projector 1 of the front screen 2, fine concave surfaces 6 close to an aspherical surface, for example, a parabolic surface or an elliptic surface as shown in FIG. And, it is provided uniformly over the entire surface. The ray incident on the concave surface 6 has a line orthogonal to the plane of the incident point and a concave surface 6 at the same angle δ as the incident angle γ, as shown in FIG.
Is reflected by, and when it goes out from the concave surface 6 by the repetition,
The emission angle θ is different from the initial incident angle γ.

Therefore, if the curved surface of the concave surface 6 is set so that the outgoing angle θ becomes an angle toward the viewpoint 5,
The main reflection direction of the image on the front screen 2 can be directed toward the viewpoint 5. Therefore, since the reflected light is directed to the vicinity of the viewpoint 5, the maximum gain can be obtained in this direction and a bright screen can be obtained, and a clear image can be obtained even if the ambient environment has a certain brightness. It is what is done.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, a thin film 7 having diffusivity is provided on the front surface of the fine concave surface 6 of the front screen 2 of the previous embodiment, and when the incident light and the outgoing light pass through the thin film 7, the thin film 7 diffuses. Diffuses light according to its nature,
The gain difference between the center and the edge, which occurs when the reflection of the front screen 2 is parallel or has a small diffusivity, is compensated for, and the difference in light and darkness due to the gain difference of the entire front screen 2 is reduced.

FIG. 4 shows an embodiment in which the curved surface of the concave surface 6 is a part of a parabolic surface or an elliptical surface. In this case, the incident light incident on this curved surface is irrespective of the incident angle. Since the light is emitted in the focal direction of the paraboloid or the ellipsoid, it is made parallel to the direction perpendicular to the front screen 2 so that the viewpoint 5 is within the vertical width of the front screen 2.

Further, FIG. 5 is a front view of the front screen 2 of the fourth embodiment. In this embodiment, the front screen 2 is divided into three vertical surfaces 2a, 2b, 2c.
The curved surface of the concave surface 6 is changed for each divided surface. That is, for example, when the viewpoint 5 is near the upper and lower centers of the front screen 2, the curved surface of the concave surface 6 is a parabolic surface or an elliptical surface in the divided central surface 2b, and the reflection direction on this surface 2b is Aim at the viewpoint 5 located at the upper and lower center of the front screen 2.

Then, the central surface 2b can have the highest gain obtained by the front screen 2, and the surface 2b becomes a bright screen. Then, in the upper surface 2a, the curved surface of the concave surface 6 is approximated to a parabolic surface or an elliptic surface, but the outgoing angle is slightly downward, and the lower surface 2c is similarly subjected to the outgoing angle. Should be slightly upwards.

Then, since the upper and lower surfaces 2a and 2c also become reflected light toward the viewpoint 5, the same gain as the central surface 2b can be obtained on the upper and lower surfaces 2a and 2c, and the brightness of the screen due to the difference in gain between the upper and lower surfaces. Difference does not occur.

FIG. 6 is a front view of the front screen 2 showing the fifth embodiment. A rectangular divided surface is obtained by adding upper and lower dividing lines to the vertical division of the fourth embodiment. 2d, a U-shaped surface 2e that surrounds the surface 2d with three sides,
The surface 2e is divided into a U-shaped surface 2f surrounded by three sides.

Then, similarly to the fourth embodiment, if the reflection directions of the surfaces 2d, 2e, 2f are directed to the viewpoint 5, the gain at the center of these surfaces can be increased to the maximum. Is possible, and because of the highest brightness that can be obtained on the front screen 2 and there is no gain difference,
It is possible to make an image with little brightness.

[0029]

As described above, according to the present invention, the incident light surface of the front screen is provided with a fine aspherical concave surface which is uniformly and finely spaced in the entire direction. Can be reflected.

Therefore, the installation position of the projector is
Even if the position is vertically separated from the viewpoint, the curved surface of the concave surface can be changed to direct it to a viewpoint different from the incident angle to the front screen, and the maximum gain at the viewpoint can be obtained.

Therefore, the maximum gain of the front screen can be obtained from the viewpoint, a bright screen can be obtained, a high-contrast, easy-to-see image can be obtained, and the surrounding environment need not be so dark. Further, the projector may be installed at any place such as on the ceiling.

Further, if the front screen is made up of a plurality of divided surfaces and the reflection direction is directed to the viewpoint for each surface, a gain difference due to insufficient light diffusion between the center and the edge of the screen is generated. By setting the difference in brightness between the divided surfaces to be substantially the same, it is possible to prevent such a difference in brightness from occurring.

[Brief description of drawings]

FIG. 1 is a side view showing a projection time when a front screen according to a first embodiment of the present invention is used.

FIG. 2 is an enlarged cross-sectional view of a part of the front screen of the above.

FIG. 3 is an enlarged cross-sectional view when a diffusible thin film is provided on the surface of the above front screen.

FIG. 4 is an enlarged cross-sectional view showing the relationship between the angles of incident light and emitted light when the concave surface of FIG. 2 is a parabolic surface or an elliptical surface.

FIG. 5 is a front view of a front screen according to a fourth embodiment of the present invention.

FIG. 6 is a front view of a front screen according to a fifth embodiment of the present invention. It is a figure.

FIG. 7 is a side view when a conventional screen having the same incident angle and the same outgoing angle is used.

FIG. 8 is an explanatory diagram for incident light of glass beads.

FIG. 9 is a side view when a conventional bead screen is used.

[Explanation of symbols]

 1 Projector 2 Front screen 2a, 2b, 2c, 2d, 2e, 2f Divided surface 3 Glass beads 5 Viewpoint 6 Concave surface

Claims (3)

[Claims] 1. A front screen, comprising a fine aspherical concave surface uniformly and finely distributed over the entire surface of the screen on the projection surface side from a projector. 2. The projection surface side of the screen from the projector is defined as a plurality of divided surfaces, and each divided surface has:
A front screen characterized in that each surface is provided with a fine aspherical concave surface that is uniformly and finely distributed over the entire surface and has different curved surfaces. 3. A projection surface side of a screen from a projector is a rectangular shape in which horizontal and vertical lines intersect, and a plurality of U-shaped surfaces surrounding the rectangular shape are divided into a plurality of U-shaped surfaces. A front screen, characterized in that each surface is provided with a fine aspherical concave surface which is uniformly and finely distributed over the entire surface and has different curved surfaces.