JPH0380236A - Transparent screen for projection television and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a bright screen by providing a lenticular lens with a transparent thermoplastic resin in the form of a sheet and a transparent spherical bead layer having the refractive index larger than the refractive index of this transparent thermoplastic resin. CONSTITUTION:The lenticular lens 1 is constituted by incorporating an inorg. diffusing agent 3 into a sheet material 2 consisting of the transparent thermoplastic resin and further disposing the transparent spherical beads which are incompatible with the transparent thermoplastic resin 2 and have the refractive index larger than the refractive index of the transparent thermoplastic resin 2 to the surface of the cylindrical lenses of the lenticular lens 1 for the transmission type screen. The vertical view angle is enlarged by the transparent spherical beads 4. The bright screen is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a Fresnel lens and a lenticular lens used in a so-called transmission type projection television device in which an image is projected from the back side and the image transmitted through the screen is observed from the front side. The present invention relates to a combination transmissive screen, especially its lenticular lens.

2. Description of the Related Art In the past, various types of transmission screens have been proposed for use in projection television apparatuses, and some have already been put into practical use. A typical type of transmissive screen today is a transmissive screen that combines a Fresnel lens and a lenticular lens.This screen uses a Fresnel lens to transmit images projected from the three-color CRT (red, green, and blue) of a projection television. to make it almost parallel light,
The structure is such that the light enters a lenticular lens and the viewing angle is expanded by a cylindrical lens on the surface of the lenticular lens.

Problems to be Solved by the Invention Lenticular lenses that expand the viewing angle described above generally have a large number of cylindrical lenses on the surface of a transparent thermoplastic resin sheet mixed with a diffusing agent. On the other hand, the upper and lower viewing angles (vertical viewing angles) are expanded using a diffusing agent, but there is a problem in that the vertical viewing angles are insufficient.

As a way to solve this problem, it is possible to expand the vertical viewing angle to some extent by increasing the amount of diffuser mixed in, but the larger the amount of diffuser, the greater the light loss. Therefore, there is a limit to the extent to which the vertical viewing angle can be expanded.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a lenticular lens using a sheet material in which a diffusing material such as silica powder is mixed into a transparent thermoplastic resin, and a sheet material on the incident side or the exit side. A transparent spherical bead layer having a refractive index higher than that of the transparent thermoplastic resin is disposed on either surface.

Effects According to the above configuration, the surface of the lenticular lens for a transmission screen can be made highly light diffusive without using a large amount of diffusing agent because the lens effect of the transparent spherical beads is utilized. Not only the width of diffusion in the horizontal direction but also the width of diffusion in the vertical direction can be significantly expanded, and since there is no total reflection and the loss of the amount of transmitted light is extremely small, it is possible to provide a bright screen on a projection television.

Embodiment Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a lenticular lens for a transmission type screen according to the present invention, and FIG. 2 is a sectional view showing a manufacturing process for providing a lenticular lens for a transmission type screen. As shown in FIG. 1, the lenticular lens 1 for a transmission screen of this embodiment has an inorganic diffusing agent 3 mixed into a sheet material 2 made of a transparent thermoplastic resin, and is further incompatible with the transparent thermoplastic resin 2. Transparent spherical beads 4 that are soluble and have a refractive index greater than that of the transparent thermoplastic resin 2
is arranged on the surface of the cylindrical lens of the lenticular lens 1 for a transmission screen, and the vertical viewing angle is enlarged by the transparent spherical beads 4.

The transparent thermoplastic resin 2 for forming the lenticular lens 1 for a transmission screen is, for example, an acrylic resin, a styrene resin, an acrylic-styrene copolymer resin, or a vinyl chloride resin.

Polyolefin resin, polyester resin, polycarbonate resin, and various other transparent thermoplastic resins can be used.

The transparent spherical beads 4 arranged on the surface of the cylindrical lens of the lenticular lens 1 of the transparent thermoplastic resin 2 are not compatible with the transparent thermoplastic resin 2, that is,
In the manufacturing method shown in FIG. 2, it is important that the shape is not lost due to the temperature of the mold and the heated transparent thermoplastic resin 2.

Furthermore, it is necessary that the refractive index of the transparent spherical beads 4 be larger than the refractive index of the transparent thermoplastic resin 2. When the refractive index is small, total reflection occurs, and the reflection loss of light becomes large at the interface between the transparent spherical beads 4 and the transparent thermoplastic resin 2, resulting in a large loss in the amount of transmitted light. will not be achieved.

The transparent spherical beads 4 having the above conditions are made by crosslinking glass beads having a higher refractive index than the transparent thermoplastic resin 2, various transparent non-thermoplastic resins whose refractive index is largely adjusted, or various transparent thermoplastic resins. beads can be used.

In the lenticular lens 1 for a transmission type screen, transparent spherical beads 4 whose refractive index is largely adjusted are placed on the surface of the cylindrical lens of the lenticular lens 1 for a transmission type screen by at least 10% of the surface area of the cylindrical lens.
It has been experimentally confirmed that a good reproduced (projected) image can be obtained with the above arrangement.

Further, the particle size of the transparent spherical beads is preferably 50 μm or more and 173 or less of the diameter of the cylindrical lens.

The lenticular lens 1 for a transmission screen having the material and structure as described above is provided by a manufacturing process as shown in FIG.

In the first step of FIG. A sheet material 2 made of a transparent thermoplastic resin heated to a temperature close to the heat deformation temperature of the transparent thermoplastic resin is inserted between the lower mold 5 and the upper mold 6, and the lower mold 5 and the upper mold 6 are When heated to near the melting temperature (glass transition point) of the transparent thermoplastic resin of the sheet to be used and press started as in the second step, the surface of the sheet material 2 made of transparent thermoplastic resin forms the transparent spherical beads 4 in the center. When pressed, the transparent spherical beads 4 spread along the cylindrical lens forming surface 7.

In the third step, the sheet material 2 made of a transparent thermoplastic resin melted by the lower mold 5 and the upper mold 6 flows into the gaps between the beads to form the final shape of the lenticular lens 1 for a transmission screen. Ru. Then, while maintaining this state, the lower mold 5 and the upper mold 6 are cooled, and when the sheet material 2 made of transparent thermoplastic resin is cured, the lower mold 5 and the upper mold 6 are cooled.
Open it and take out the lenticular lens 1 for transmission type screen. The surface condition of the cylindrical lens of the lenticular lens 1 for a transmission type screen made in this way is such that the transparent spherical beads 4 are not necessarily neatly arranged as shown in FIG.

Therefore, the sheet material 2 made of the transparent thermoplastic resin melted by the lower mold 5 and the upper mold 6 always flows into the gaps 9 between the beads. In such a case, if the refractive index of the transparent spherical beads 4 is smaller than that of the sheet material 2 made of transparent thermoplastic resin, total reflection will occur at the interface between the sheet material 2 made of transparent thermoplastic resin and the transparent spherical beads 4. Therefore, the purpose of the present invention is to transmit light through the transparent spherical beads 4 and expand the vertical viewing angle by utilizing the effect of the transparent spherical beads 4 acting as a lens when the light is emitted from the transparent spherical beads 4. The refractive index must necessarily be greater than that of the sheet material 2 made of transparent thermoplastic resin.

On the other hand, when the manufacturing mold is reversed and the transparent spherical beads 4 are placed on the surface of the exit side lenticular lens 8 having a black stripe convex portion to enlarge the vertical viewing angle on the exit side, the refraction of the transparent spherical beads 4 is similarly applied. The ratio must be greater than that of the sheet material 2 made of transparent thermoplastic resin.

Effects of the Invention According to the present invention as described above, since the lens effect of transparent spherical beads is utilized in the production of a lenticular lens for a transmission screen, the surface of a lenticular lens for a transmission screen can be highly improved without using a large amount of diffusing agent. Since it can be made light diffusive, it is possible to significantly expand the diffusion width in the vertical direction as well as the horizontal diffusion width with a lenticular lens, and there is no total internal reflection, resulting in extremely low loss of transmitted light, making it bright for projection TVs. It is possible to provide a screen.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a lenticular lens for a transmission screen of the present invention, FIG. 2 is a sectional view showing the manufacturing process of the lenticular lens for a transmission screen of the invention, and FIG. 3 is a sectional view of a lenticular lens for a transmission screen of the invention. It is a detailed sectional view showing a state in which transparent spherical beads are arranged on the surface of a cylindrical lens of a lenticular lens. DESCRIPTION OF SYMBOLS 1...Tendicular lens for transmission screen, 2...Sheet material made of transparent silent plastic resin, 3...Inorganic diffusing agent, 4... ...Transparent spherical beads, 7... Cylindrical lens forming surface.

Claims (2)

[Claims] (1) In a transmission screen constructed by combining two lenses, a Fresnel lens and a lenticular lens, the lenticular lens consists of a sheet-like transparent thermoplastic resin mixed with a diffusing material such as silica powder, and an incident light beam of the transparent thermoplastic resin. 1. A transmission screen for a projection television, comprising: a transparent spherical bead layer having a refractive index higher than that of the transparent thermoplastic resin disposed on at least one surface of the side or the output side. (2) Transparent spherical beads are placed on the surface of the cylindrical lens forming part of the lenticular lens in the lenticular lens production mold, and a sheet material in which a diffusing material such as silica powder is mixed into heated transparent thermoplastic resin is used to form a lenticular lens. A method for manufacturing a transmission screen for a projection television, characterized by forming a lenticular lens by inserting it into a production mold and hot pressing, and arranging transparent spherical beads on the surface of the cylindrical lens of the lenticular lens.