JPH05333304A - Liquid crystal rear projection television receiver - Google Patents

Abstract

PURPOSE:To improve the reliability of a circularly polarized light filter and to obtain images with high contrast. CONSTITUTION:This television receiver is provided with a 1/4 wavelength board 16 to turn projecting light composed of the linearly polarized beams of liquid crystal panels 13R, 13G and 13B to circularly polarized beams in R, G and B having the same rotating direction, between the liquid crystal panels 13R, 13G and 13B and a screen 15, and the screen 15 is composed of a Fresnel lens sheet 151, renticular lens sheet 152, and circularly polarized light filter sheet 153 for which the 1/4 wavelength board to turn projecting light composed of circularly polarized light in a single direction to linearly polarizing light and a polarizing board provided with the same polarizing axis as the projecting light converted to linearly polarized light are attached to a core member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal rear projection television. In particular, the present invention relates to a liquid crystal rear projection television composed of a TN type liquid crystal panel.

[0002]

2. Description of the Related Art Conventional LCD rear projection televisions are
It basically had the same structure as the CRT rear projection TV. The difference is that a liquid crystal panel is used instead of the CRT, which requires a light source and a color separation optical system.

Of conventional liquid crystal rear projection televisions
The configuration is shown in FIG. 2 and will be described. I.e. usually meta
The luminous flux l1 from the light source 21 using the Lu Halide lamp is
Color separation optical system 2 composed of an icroic filter
3 colors of R, G, B depending on 2 _R, L_G, L_BDisassemble into
It The decomposed R, G, B lights are the corresponding liquids.
Crystal panel 23R, 23G, 23B is incident on it to control the brightness.
Controlled. Controlled monochromatic light flux l_R1, L_G1, L_B1Throw
It becomes a light. This projection light l_R1, L_G1, L_B1Is the projection lens
Connected to the screen 25 through the 24R, 24G, 24B
Imaged and displayed. Screen 25 is a normal frame
Ren equipped with flannel lens 251 and black stripe
On the screen composed of a combination of chicula-lens 252
The brightness and viewing angle characteristics of are secured.

Since the structure of this conventional example has a problem that the effect of external light and the glossiness of the surface cannot be sufficiently obtained, the structure of the conventional example 2 (FIG. 3) is used. The configuration numbers in the figure are the same as (FIG. 2). That is,
The screen 25 is provided with a tint glass 253 having an antireflection coating on its outermost surface. With this configuration, it is possible to reduce the effect of glossiness and the influence of outside light.

In the structure of Conventional Example 2, a glossy feeling is obtained, but the reduction in contrast due to the influence of external light is contrary to the transmittance of the tint glass 253 and is not satisfactory. That is, when the transmittance is set to 70%, the reflected light is reflected by the reflecting surface in the screen, and 49% is returned, so that the contrast of the screen cannot be said to be satisfactory.

As a means for improving this point, a circular polarization screen was invented (application request number H03-0233).
A conventional example 3 is shown in FIG. 4 and will be described. The basic structure is the same as that of the conventional example 1, but the screen is composed of two Fresnel lens sheets 251 and a lenticular lens sheet 40. The lenticular lens sheet 40 is provided with a light diffusing layer 41a. -A lens 41 and a quarter wave plate 42 and a polarizing plate 43 are attached to the outermost surface of the lens 41. When the screen of this configuration is used and the projection light from the liquid crystal panel is formed in the same rotation direction, for example, left-handed circularly polarized light by using the quarter-wave plate, the projection light is 1/4 of the screen.
Since it is converted into linearly polarized light by the wave plate 42 and the polarization optical axis of the polarizing plate 43 and the polarization axis of the projection light are aligned with each other, the parallel transmittance of the polarizing plate 43, for example, 80 to 90% is transmitted. On the other hand, the external light is cut off due to the characteristics of the circular polarization filter. That is, the external light is cut by 50% or more by passing through the polarizing plate 43 to become linearly polarized light.
Further, the light passes through the quarter-wave plate 42 to become one rotation direction, for example, left circularly polarized light, and when reflected by the diffusion layer 41a, becomes right circularly polarized light. The right-handed circularly polarized light returns to linearly polarized light by passing through the quarter-wave plate 42, but since the polarization axis of this linearly polarized light is orthogonal to the polarization axis of the polarizing plate 43, it is almost absorbed by the polarizing plate. .. Therefore, the glossiness and contrast of the screen can be sufficiently obtained.

[0007]

In the liquid crystal rear projector shown in the conventional example 3, for example, in the case of a 40-inch screen and 640 horizontal pixels, the black matrix of the liquid crystal panel is projected at a pitch of 1.3 mm. It A lenticular lens having a fine pitch of 0.2 to 0.3 mm or less is required to eliminate moire due to the interference between the black matrix and the lenticular lands. In this case, in order to prevent blurring of the projected image, the plate thickness of the lenticular lens must be 2 mm or less and the diffusion layer must be provided. Since the lenticular lens has irregularities, the plate thickness of the concave portion is thin and the physical strength is reduced. The quarter-wave plate has a problem that when a strong physical tension is applied, its characteristics change and the performance as a circular polarization filter deteriorates. Therefore, in the configuration of the above-mentioned conventional example 3, when the number of horizontal pixels of the liquid crystal panel is further increased, the pitch of the lenticular lens needs to be further miniaturized, so that the strength of the lenticular lens is insufficient and the contrast, particularly the contrast around the projection screen is lowered. There was a problem that occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a liquid crystal rear projector using a high-density liquid crystal panel, which is capable of obtaining an image with sharpness without a decrease in contrast. To do.

[0009]

In order to achieve the above object, a liquid crystal rear projector according to the present invention will be described below. That is, a light source, color separation means for color-separating into three colors of R, G, B, a liquid crystal panel for controlling light fluxes of R, G, B, and R, G, B projection light from the liquid crystal panel are color-coded. Projection light composed of a projection lens for synthesizing and tying, and a screen provided on the tying surface of the projection lens, and a linearly polarized light of the liquid crystal panel between the liquid crystal panel and the screen. Is a circularly polarized light having the same rotation direction in R, G, and B, and the screen is a Fresnel lens sheet, a lenticular lens sheet, and the circularly polarized light in the single direction. Circular polarization filter with a quarter wavelength plate for converting the projection light into linearly polarized light and a polarizing plate having the same polarization axis as the projection light converted into the above linearly polarized light to a core material.
And a configuration including

Particularly, the core material is made of tempered glass or acrylic resin and surface-hardened acrylic resin.

[0011]

[Operation] This operation is as follows. That is, the luminous flux from the light source is separated into three colors of R, G, and B by the color separation means, and the projection lights of three colors of R, G, and B controlled by the liquid crystal panel are made the same by using the 1/4 wavelength plate. The direction of rotation, for example left circularly polarized light, is formed. That is, the projection light is left circularly polarized light of three colors of R, G, and B. The projection light consisting of this left circularly polarized light is
Since it is converted to linearly polarized light by the 1/4 wavelength plate in the lens, the polarization optical axis of the polarizing plate and the polarization axis of the projection light are made to match.
The parallel transmittance of the polarizing plate, for example, 80 to 90% is transmitted. In this case, since a tempered glass having a plate thickness of 3 mm or an acrylic resin and a surface-cured acrylic resin are used as the core material, there is no birefringence and the polarization property is maintained, so that the parallel transmittance of the polarizing plate is maintained. .. At the same time, since it has sufficient physical strength, it does not change the characteristics of the quarter-wave plate, and therefore maintains the performance as a circular polarization filter.

On the other hand, since the external light uses the circular polarization filter having the above-mentioned stable characteristics, the external light is sufficiently cut.
That is, the external light is cut by 50% or more by passing through the polarizing plate to become linearly polarized light. Further, by passing through the quarter-wave plate, it becomes one rotation direction, for example, left circularly polarized light,
When it is reflected by the diffusion layer provided on the lenticular sheet, it becomes right circularly polarized light. Right circularly polarized light returns to linearly polarized light by passing through the quarter-wave plate, but since the polarization axis of this linearly polarized light is orthogonal to the polarization axis of the polarizing plate, it is almost absorbed by the polarizing plate. Therefore, the glossiness and contrast of the screen can be sufficiently obtained.

[0013]

EXAMPLE An example of the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing a configuration of a main part of the present invention.
is there. Light source 11 and R consisting of metal halide lamp,
A dichroic filter that separates G and B into three colors?
Color separation means 12 and a light flux l of R, G, B_R,
l_G, L_BFor controlling liquid crystal panels 13R, 13G, 13
B and R from the liquid crystal panels 13R, 13G, 13B,
Projection lens 14 for synthesizing and synthesizing G and B projection lights
And a screen 15 provided on the surface of the projection lens 14
Consists of LCD panel 13R, 13G and 13B.
Liquid crystal panels 13R, 13G, 1 between the cleaner 15 and
Projection light 1 consisting of 3B linearly polarized light_R1, L_G1, L_B1R,
Circularly polarized light l having the same rotation direction in both G and B_R2, L _G2,
l_B2The quarter wave plate 16 and the screen 15
Nell lens sheet 151 and lenticular lens sheet
Projection light 1 consisting of 152 and circularly polarized light in the above-mentioned single direction_R2, L
_G2, L_B2Linearly polarized light and the above linearly polarized light
A polarizing plate having the same polarization axis as the projected light converted to
A circular polarization filter attached to a 3 mm thick acrylic core.
It is composed of a terminal sheet 153.

With the above-mentioned structure, an image having a large contrast and a good sharpness can be obtained with little influence of external light even on a black display screen. And circular polarization filter
Even when the sheet was firmly attached to the set, no deterioration in characteristics was observed.

The structure of the circularly polarized light filter sheet is shown in FIG.
Will be described. In the figure (a), the core material 51 has a plate thickness of 3 mm.
The hard coat treated acrylic resin is used and the quarter wavelength plate 52 and the polarizing plate 53 are attached to the incident side of the projection light.
Since the acrylic is hard-coated, the surface is less likely to be scratched, and there is no problem with the characteristics of the circular polarizing filter sheet.

FIG. 2B shows a structure in which a non-reflective coating 54 is added to the structure of FIG. In the figure, 51, 52 and 53 are the same as those in FIG. With this configuration, a clear image with less reflection of external light was obtained. There was no problem in the characteristics of the circularly polarized light filter-sheet, and the black screen was sufficiently sunk. In this structure, the same effect can be obtained whether the core material 51 is an acrylic resin or tempered glass.

FIG. 3C shows a plate made of acrylic having a thickness of 3 m.
In this configuration, the quarter wavelength plate 52 is provided on the projection light incident side of the m core material 51, and the polarizing plate 53 is provided on the emission side. Since acrylic has no birefringence, there is no problem in the characteristics as a circularly polarized light filter sheet, and there is no problem in the stress applied to the set attachment or the like. Also in this case, the same effect was obtained even when the tempered glass was used as the core material.

[0019]

The liquid crystal rear projector according to the present invention
Is 1 / using a core material with a plate thickness of 3 mm and no birefringence
Since the four-wave plate and the polarizing plate are attached, the physical strength is high and there is no optical anisotropy. For this reason, the characteristics of the circularly polarized light filter do not change, and there is an effect that an image with good sharpness can be obtained with high reliability, with little influence of external light.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a liquid crystal rear projector according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of main parts of a liquid crystal liquid crystal rear projector of Conventional Example 1.

FIG. 3 is a configuration diagram of main parts of a liquid crystal liquid crystal rear projector of Conventional Example 2.

FIG. 4 is a configuration diagram of a main part of a screen used in a liquid crystal liquid crystal rear projector of Conventional Example 2.

FIG. 5 is a configuration diagram of a main part of a circular polarization filter sheet used in a liquid crystal rear projector according to an embodiment of the present invention.

[Explanation of symbols]

 11 Light Source 12 Color Separation Means 13 Liquid Crystal Panel 13R R Liquid Crystal Panel 13G G Liquid Crystal Panel 13B B Liquid Crystal Panel 14 Quarter Wave Plate 15 Screen 151 Fresnel Lens Sheet 152 Lenticular Lens Sheet 153 Circular Polarization Filter -Sheet

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 9/31 B 8943-5C

Claims (4)

[Claims] 1. A light source, color separation means for color separation into three colors of R, G and B, a liquid crystal panel for controlling light fluxes of R, G and B, and projection of R, G and B from the liquid crystal panel. A liquid crystal rear projection television comprising a projection lens for color-synthesizing light to form a light and a screen provided on a connection surface of the projection lens, wherein the liquid crystal panel is provided between the liquid crystal panel and the screen. The projection light consisting of linearly polarized light of
Circularly polarized light having the same rotation direction in both G and B 1/4
The wave plate and the screen are converted into the quarter-wave plate and the above-mentioned linearly polarized light, which is the Fresnel lens sheet, the lenticular lens sheet, and the circularly polarized light in the unidirectional direction, which makes the projection light linearly polarized light. A liquid crystal rear comprising a circular polarization filter sheet in which a polarizing plate having the same polarization axis as the projected light is attached to a core material made of tempered glass or acrylic resin and surface-hardened acrylic resin. Projection television. 2. The circular polarization filter sheet according to claim 1,
The liquid crystal rear projection television according to claim 1, wherein a quarter-wave plate and a polarizing plate are attached to the surface of the core material on the projection light incident side. 3. The circular polarizing filter sheet according to claim 1,
3. The liquid crystal rear projection television according to claim 2, wherein a non-reflection coating is provided on the surface of the core material on the projection light emission side. 4. The circular polarizing filter sheet according to claim 1,
The liquid crystal rear projection television according to claim 1, wherein a quarter-wave plate is attached to a surface of the core material on the projection light incident side, and a polarizing plate is attached to the projection light emitting side.