JPH05232582A - Lenticular lens for screen - Google Patents

Abstract

PURPOSE:To diverge incident light with good balance and obtain a projection surface where no bright line is generated by forming slanting surface parts of the lenticular lens by using curved surfaces and making the top part surfaces convex or concave. CONSTITUTION:At the slanting surface parts 3 between the top parts 1 and bottom parts 2 which succeed alternately, curved total reflecting surfaces are formed so that a light beam which is made incident on the parts is totally reflected and then projected from the slanting surface part of the opposite side or the top surface 1a. The top surfaces 1a are made convex or concave according to the purpose of use, preferably, so that light reaching the top surface is not totally reflected by the surface. Further, the bottom surfaces may be made convex or concave. Consequently, the projection surface which generates no bright light and has a high visual field angles is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a video projector.
The present invention relates to a lenticular lens used in a transmission type screen for automobiles.

[0002]

2. Description of the Related Art A transmission type projection screen is used as a projection surface of a display for a video projector, etc., but various studies have been made on its light transmission characteristics such as increasing the viewing angle. As one of means for achieving such an object, a lenticular lens in which a large number of minute cylindrical lenses are continuously formed is used alone or in combination with another lens or a diffusing plate.

As described above, this lenticular lens is effective in diffusing incident light, and in the case where a large number of minute cylindrical lenses are continuously formed in the vertical direction, the light is diffused in the horizontal direction and then in the horizontal direction. The one in which a minute cylindrical lens is formed has a function of diffusing light in the vertical direction.
Also, when using this lenticular lens as a screen, when the lens surface is directed to the incident light side, that is, the light source side,
The maximum diffusion angle is limited for each of the emission side, that is, the direction toward the observer side, and the diffusion angle can be increased when facing the light source side compared to when facing the observer side. Are known. However, in general, the diffusion of light by this type of lenticular lens has a narrow angle, and there is a drawback that the brightness sharply decreases at a position exceeding 30 ° from the center.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 57-207235 discloses a lenticular lens for a screen in which a peak portion and a valley portion are continuously provided, and a light ray incident on a slope portion of a medium. While a total reflection surface is formed on the slope portion so that the light is totally reflected on the slope portion and then passes through the peak portion top surface, a lenticular lens for a screen in which the peak portion top surface is formed in a concave shape is proposed. There is.

[0005]

[Problems to be Solved by the Invention]
In the lenticular lens proposed in Japanese Patent Laid-Open No. 207235, the following problems occur due to the fact that the inclined surface portion that interacts with the total reflection surface is a planar total reflection surface. (1) When the total reflection surface is flat, it is difficult to spread the light in a well-balanced manner. (2) When the totally reflected light is emitted from the total reflection surface, it becomes a bright line. In other words, they are concentrated and a large amount of emitted light is generated at the same angle. An object of the present invention is to obtain a projection surface in which light incident on a lenticular lens is spread in a well-balanced manner and bright lines are not generated.

[0006]

The present inventor has completed the present invention as a result of intensive studies in view of the above situation. That is, the gist of the present invention is a lenticular lens for a screen in which a mountain portion and a valley portion are continuously provided, and the light totally reflected on the slope portion of the lenticular is opposite to the slope portion. The slope portion is formed with a curved surface so that it is emitted from the side slope portion or the mountain top surface,
A lenticular lens for a screen characterized in that the top surface of the mountain portion is formed into a convex or concave curved surface.

The greatest feature of the present invention is the lenticular.
The point is that the slope is formed by a curved surface so that the light totally reflected on the slope can be emitted from the slope opposite to the slope or the top of the mountain. For screens obtained by doing so The lenticular lens can achieve the above object.

FIG. 1 is a perspective view seen from the projection side showing one form of the lenticular lens of the present invention. FIG. 2 is a cross-sectional plan view of the lenticular lens of FIG. In these figures, (1) is a mountain portion and (2) is a valley portion, and the mountain portion (1) and the valley portion (2) are alternately arranged in succession.
Then, in the slope portion (3) between the mountain portion (1) and the valley portion (2), the ray incident on this portion is totally reflected and then emitted from the opposite slope portion or the mountain portion top surface. A curved total reflection surface is formed. The peak top surface (1a) may be either convex or concave and can be appropriately determined according to the purpose. In addition, (4) in the figure is an opposite surface opposite to the lens surface. This shape will be described in more detail with reference to FIG. 3. This is an enlarged view of one piece of the lenticular lens of the present invention. The top surface (1a) of the mountain portion (1) has a concave shape and the inclined portion has an upper corner. 78 °, lower corner 6
A 6 ° parabolic total reflection surface is formed. When parallel light enters from the opposite surface (4) to such a lenticular lens for a screen, as shown in FIG.
The light incident on the portion (B) corresponding to the mountain portion (1) travels straight in the medium and is refracted and diffused by the lens-shaped concave surface of the top surface (1a). At this time, the light incident on the slope (3), that is, (A)
Alternatively, the light in the portion (A ′) is totally reflected by the slope portion and emitted from the top surface (1a) of the mountain portion (1) and the slope portion (3) opposite to the reflected slope. The curved surface of the inclined surface may be concave or convex as long as it can be totally reflected.

On the other hand, the shape of the top surface (1a) of the mountain portion is appropriately determined depending on the purpose, and it may be either concave or convex as shown in FIGS. 2 and 4, but it reaches this top surface. It is preferable that the reflected light is not totally reflected on this surface.

In the present invention, a lens surface may be formed on the bottom surface of the valley as shown in FIG. Referring to FIG. 5, the lens portion (2a) is formed in the valley in the lenticular lens for screen including the above-mentioned peak (1), valley (2) and slope (3). That is, as shown in FIG. 5, since the lens surface (2a) is formed on the bottom surface of the valley portion (2), the light incident on the peak portion top surface (1) (B) and the inclined portion (3) portion ( A),
The light incident on (A ′) is diffused similarly to the above-described example, but the light incident on the lens surface (2a) is further refracted and diffused. This lens surface (2a) may be a convex lens surface as shown in FIG.
It may be a concave lens surface as shown in FIG. When the lenticular surface on the observation side is irradiated with the external light beam, this lowers the contrast of the image. In order to prevent this, as shown in FIG. 7, a light absorption layer (5) for preventing reflection of external light is formed on a portion of the total reflection surface (3) where light is not emitted, so that an image that each lenticular lens faces. Can increase the contrast.
The lenticular lens according to the present invention, as described above, can have a high diffusion characteristic due to the constitution of one lens surface, and therefore it may be used alone, but the surface on the side where the light ray is incident on the medium. It is also possible to use (6) in combination. From this point of view, the surface (6) may not be a smooth surface, but may be a fine uneven surface or may be another lens surface. Examples thereof include a Fresnel lens surface and a lenticular lens surface that diffuses light in the vertical direction.

Next, the light rays projected will be described.
As shown in FIG. 3, the light in the range corresponding to the top surface (1a) of the mountain is diffused from the top surface (1a) to the area (B), and is totally reflected by the inclined portion (3) so that the top surface (1a) of the mountain portion is The light emitted from () is diffused in the range of (A), and the light emitted from the inclined part on the opposite side is diffused in the range of (A). The degree of diffusion can be variously selected depending on the pitch of the lenticular lens, the height of the crests (1), the shapes of the top surface and the inclined surface, and the like. For example, the pitch is about 0.3 m to 1.5 mm, The height of the mountain is 0.3 ~
It is good to set it to about 2 mm.

As the medium used in the lenticular lens of the present invention, acrylic resin is preferable from the viewpoint of optical characteristics and moldability, but vinyl chloride resin, polycarbonate resin, olefin resin, styrene resin and the like are used. it can. These resins can be formed into a lenticular lens according to the present invention by extrusion molding, heat pressing, or injection molding.

In order to further improve the light diffusing property of the lenticular lens according to the present invention, another diffusing means may be provided in the medium. As the diffusion means, SiO2, CaCO3, Al2O3, TiO3,
Liquid synthetic resin such as BaSO4, ZnO, fine glass powder, or organic diffusing agent. One or two or more additives of diffusing substances that do not melt or chemically change in the medium are uniformly mixed and dispersed in the medium. Alternatively, a layer containing these diffusing substances may be formed, or a fine uneven surface may be formed on the incident surface and / or the peak portion.

[0014]

EXAMPLE An acrylic resin plate having a thickness of 2 mm obtained by mixing SiO2 as a diffusing agent into an acrylic resin having a refractive index n = 1.49 was used, and this resin plate was hot press molded to obtain a product of the present invention. Two types of lenticular lenses having a configuration as shown in FIG. 8 and a configuration as shown in FIG. 8 were prepared as comparative products. The obtained lenticular lens was attached to a Mitsubishi Electric 40-inch projection TV together with a Fresnel lens, and the entire screen was observed. As a result, the one of the present invention gave a brighter screen without bright lines than the comparative product. It was The gain-θ curves are as shown in FIGS. 9A and 9B, and it can be seen that the bright line is not generated in the product of the present invention. In the product of the present invention, the gain is 2.7 and αH:
33 °, βH: 40 °, gain of comparison product: 2.7, α
H: 25, βH: 36, the αH value and βH value of the product of the present invention were higher than those of the comparative product, and the color balance was also improved.

[0015]

INDUSTRIAL APPLICABILITY The lenticular lens of the present invention is capable of obtaining a projection surface having a wide viewing angle without generation of bright lines, and can be used for a projection screen such as a projector TV.

[Brief description of drawings]

FIG. 1 is a perspective view of a lenticular lens of the present invention viewed from a projection surface side.

2 is a cross-sectional plan view of the lens of FIG.

FIG. 3 is an explanatory diagram illustrating a diffusion state of light in FIG.

FIG. 4 is a cross-sectional plan view of the product of the present invention in which the top surface of the mountain portion is convex.

FIG. 5 is an explanatory diagram illustrating a light diffusion state of the product of the present invention having a lens portion in a valley portion.

FIG. 6 is a cross-sectional plan view of the product of the present invention in which the lens portion of the valley portion forms a concave surface.

FIG. 7 is a cross-sectional plan view of a product of the present invention in which a light absorption layer is formed.

FIG. 8 is a cross-sectional plan view of a lenticular lens having a flat inclined portion.

FIG. 9 is a gain-θ curve of the product of the present invention and the comparative product.

[Explanation of symbols]

(1) Mountain part (1a) Mountain part top surface (2) Valley part (2a) Valley part lens part (3) Inclined part (4) Opposite surface (5) Light absorption layer (6) Incident surface A Reflected by inclined part The part where the reflected light is incident A'The part where the light reflected by the inclined part is incident B The part where the light that reaches directly without refracting the mountain top surface is incident

Claims (2)

[Claims] 1. A lenticular lens for a screen, wherein a mountain portion and a valley portion are continuously provided, wherein the light totally reflected on the slope portion of the lenticular is on the slope portion on the opposite side of the slope portion. A lenticular lens for a screen, characterized in that the slope portion is formed to have a curved surface so as to be emitted from the top surface of the mountain portion, and the top surface of the mountain portion is formed into a convex or concave curved surface. 2. The lenticular lens for a screen according to claim 1, wherein a convex or concave curved lens surface is formed in the valley portion.