JPH07270918A - Transmission type screen for liquid crystal projector - Google Patents

Abstract

PURPOSE:To provide a transmission type screen for liquid crystal projector which has a smaller glittering feel and is capable of efficiently preserving the polarization characteristics of projecting light. CONSTITUTION:This transmission type screen for liquid crystal projector has a Fresnel lens 2 having a lens face on the observation side 1, a one-side lenticular lens 4 which has a lens face on the incident side 3 and has a pitch <=0.2mm and a polarization screen 7 which is formed by adhering a polarizing film to an acrylic plate 5 and is arranged on the observation side of this lenticular lens. The projecting light is well transmitted and the external light is strongly absorbed when the polarization direction of the polarizing screen is aligned to the polarization direction of the projecting light 8. The lenticular lens 4 is formed by compounding glass beads having an average grain size of 0.8 to 4.5mum as diffusing agents at 0.1 to 0.7wt.% with a PMMA and molding the mixture by casting. The observation surface has a center line average surface roughness of 0.8 to 2.5mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive screen for a liquid crystal projector, and more particularly to a high resolution transmissive screen for a liquid crystal projector.

[0002]

2. Description of the Related Art Conventionally, in this type of transmissive screen for a liquid crystal projector, the light diffusion characteristic is similar to that of a CRT projector, but the lenticular lens has a small pitch to prevent moiré with the projection pixel of the liquid crystal. Especially in a high-resolution LCD projector, it becomes very small. Therefore, it is difficult to manufacture a double-sided lenticular lens or a total reflection type lenticular lens having a complicated shape by extrusion molding or compression molding. In that respect, a simplex single-sided lenticular lens is suitable, and this was combined with a Fresnel lens to form a two-element screen.

[0003]

This conventional transmissive screen for a liquid crystal projector has a problem that glare becomes more noticeable because the light diffusion characteristics of the lenticular lens are the same as those for a CRT projector.

Further, when the lenticular lens is formed by extrusion molding or compression molding, the die shape cannot be accurately transferred when the pitch is 0.2 mm or less, and the polarization characteristics of the projection light of the liquid crystal projector can be efficiently preserved due to the influence of the molding. However, there is a problem that light loss increases when combined with a polarizing screen.

An object of the present invention is to provide a transmissive screen for a liquid crystal projector that eliminates these problems.

[0006]

In order to eliminate the above-mentioned problems, a transmissive screen for a liquid crystal projector according to the present invention comprises a Fresnel lens and a lenticular lens.
In a transmissive screen for a liquid crystal projector, wherein the lenticular lens is a single-sided lenticular lens having a pitch of 0.2 mm or less, the lenticular lens is made of polymethylmethacrylate (PMM).
0.1 to 0.7% by weight of glass beads having an average particle diameter of 0.8 to 4.5 μm was blended with A) as a diffusing agent, and molding was performed by casting. The observation surface has a center line average roughness of 0. .8-2.
It is characterized by being a molded product having a surface roughness of 5 μm.

Here, 0.2 to 10% by weight of polystyrene may be added to the glass beads as a diffusing agent.

The lens portion of the one-sided lenticular lens may be molded by UV resin.

Alternatively, a polarizing screen may be arranged on the observation side to form a three-sheet structure.

[0010]

[Function] The pitch of the single-sided lenticular lens is 0.2 m.
Set m or less to prevent moire with the projection pixel. As a diffusing material, glass beads having an average particle diameter of 0.8 to 4.5 μm are used in an amount of 0.1 to 0.1 μm.
0.7% by weight is blended, and the observation surface has a center line average roughness of 0.8 to
The surface roughness of 2.5 μm eliminates glare,
Unlike the case of extrusion processed or compression molded molded product, the molded product made by liquid crystal casting accurately transfers the mold shape and efficiently preserves the polarization characteristics of the liquid crystal projector projection light. Prevents the loss of light when combined with.

[0011]

The present invention will now be described with reference to the drawings, but it goes without saying that the present invention is not limited to the embodiments.

FIG. 1 is a perspective view showing an embodiment of the present invention. An observation side 1 of the one-sided lenticular lens 4 is a polarizing screen 7 composed of a Fresnel lens 2 having a lens surface on the observation side 1, a one-sided lenticular lens 4 having a lens surface on the incident side 3 and a polarizing film 6 bonded to an acrylic plate 5. To be a three-sheet structure. The projection light 8 is polarized, and the projection light can be well transmitted by aligning the polarization direction of the polarizing screen 7 with the polarization direction of the projection light 8, but external light that strongly reduces the contrast of the image such as illumination is strongly absorbed. Can have

Next, a method of forming a single-sided lenticular lens will be described. Pigment on PMMA resin, glass beads or glass beads + polystyrene as diffusing agent,
A mixed solution of azoisobutyronitrile (AIBN) is added as a curing agent and stirred. The PMMA mixed solution is poured into a mold in which a glass plate having a matt surface and a mold of a lenticular lens are combined with a polyvinyl chloride gasket. Put this in an air furnace and hold at 70 ℃ for 6 hours, 11
After holding at 0 ° C. × 2 hours for polymerization and cooling, it is taken out from the mold and cut into a width of 1280 × a length of 720 × a plate thickness of 1 (mm). When the lens portion is made of UV resin, the mold is formed as a flat plate without a lens surface, the lenticular lens mold is attached to the finished flat plate, UV resin is put therein, and ultraviolet rays are irradiated to cure the UV resin.

The experimental results obtained by using these screens are shown in Table 1.
Shown in. As is clear from Table 1, Examples 1 to 4 have less glare than Comparative Examples and have good preservation of polarized light. Even if the pitch is 0.2 mm or less, the transfer state of the mold is good. Furthermore, when polystyrene was mixed, the mixing of the diffusing agent became more uniform. In addition, when the UV resin is used, the resin mold can be taken from the mold, so that there is no problem such as roughening of the mold. With the three-sheet structure, the reflected light of the extraneous light on the lens surface can be removed, so that the contrast can be increased.

[0015]

[Table 1]

[0016]

As described above, the screen for a liquid crystal projector according to the present invention has an average particle size of 0.8 to 4.5 μm in which a lenticular lens is used as a diffusing agent in PMMA.
0.1% to 0.7% by weight of glass beads are mixed and molded by casting, and the observation side surface has a center line average roughness of 0.8.
Since the surface roughness is up to 2.5 μm, the pitch of the lenticular lens can be 0.2 mm or less, and it can be applied to a high-resolution liquid crystal projector. Since there is little glare and the state of polarization preservation is good, there is an effect that the efficiency of light utilization is good when combined with a polarizing screen.

Uniformity of the mixing of the diffusing agent is improved by adding 0.2 to 10% by weight of polystyrene to the glass beads as the diffusing agent.

U of the lens portion of the single-sided lenticular lens
Molding with V resin can prevent the mold from being roughened, so that the shape stability is improved.

By arranging the polarizing screen on the observation side to form three plates, the reflected light on the lens surface of the external light can be absorbed and removed, so that the contrast is improved.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a transmissive screen for a liquid crystal projector of an embodiment.

[Explanation of symbols]

 1 Observation side 2 Fresnel lens 3 Incident side 4 Incident side single-sided lenticular lens 5 Acrylic plate 6 Polarizing film 7 Polarizing screen 8 Projection light

Claims (4)

[Claims] 1. A transmissive screen for a liquid crystal projector comprising a Fresnel lens and a lenticular lens, wherein the lenticular lens is a single-sided lenticular lens having a pitch of 0.2 mm or less, wherein the lenticular lens is polymethylmethacrylate and a diffusing agent. As a result, 0.1 to 0.7% by weight of glass beads having an average particle diameter of 0.8 to 4.5 μm was blended, and molding processing was performed by casting. The observed surface has a center line average roughness of 0.8 to 2. A transmission screen for a liquid crystal projector, which is a molded product having a surface roughness of 5 μm. 2. A transmissive screen for a liquid crystal projector according to claim 1, wherein 0.2 to 10% by weight of polystyrene is added to the glass beads as a diffusing agent. 3. The transmissive screen for a liquid crystal projector according to claim 1, wherein the lens portion of the one-sided lenticular lens is molded with UV resin. 4. The transmissive screen for a liquid crystal projector according to claim 1, wherein a polarizing screen is arranged on the viewing side to form three sheets.