JPH0511247A - Projection type video display device - Google Patents

Abstract

PURPOSE:To obtain superior white balance and reproduce natural colors by transmitting ultraviolet rays through at least a projection-side polarizing plate between polarizing plates. CONSTITUTION:The projection type video display device is equipped with three liquid crystal panels 31R, 31G, and 31B where images to be projected on a screen are displayed, a light source 10 which projects source light L on the liquid crystal panels 31R, 31G, and 31B, and a reflection system 20 which guides the source light L from the light source 10 to the respective liquid crystal panels 31R, 31G, and 31B. In this case, the three liquid crystal panels 31R, 31G, and 31B are in the same structure, so, for example, the liquid crystal panel 31R has a liquid crystal cell 311R wherein liquid crystal 315 is charged, and an incidence-side polarizing plate 313R and a projection-side polarizing plate 314R provided on the incidence side and projection side of the liquid crystal cell 311R respectively and the projection-side polarizing plate 314R transmits ultraviolet rays. The liquid crystal panel 31R is therefore improved in the transmissivity of a short-wave side component corresponding to a component LB of the source light L. Namely, the component LB which is used to display the image becomes larger in quantity than conventional.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection-type image display device using a liquid crystal panel for displaying an enlarged image, and more particularly to a projection-type image display device excellent in white balance and capable of reproducing natural colors.

[0002]

2. Description of the Related Art A conventional projection type image display device is shown in FIG.
Also, description will be made with reference to FIG. Some projection type image display devices of this type use three liquid crystal panels 31R, 31G and 31B of red, green and blue (hereinafter referred to as R, G and B). This projection type image display device corresponds to a light source 10 that emits a light source light L, a reflection system 20 that decomposes the light source light L into respective components LR, LG, and LB, and an image to be magnified and projected corresponds to R, G, and B. LCD panels 31R, 31G, 31B displayed as
And a magnifying projection lens system 40 that superimposes the respective components LR, LG, and LB transmitted through the three liquid crystal panels 31R, 31G, and 31B and magnifies and projects them on a screen (not shown).

The reflection system 20 has a component L as shown in FIG.
First dichroic mirror that transmits only G and LB
211, a second dichroic mirror 212 that transmits only the component LG, a third dichroic mirror 213 that transmits only the component LR, and a fourth dichroic mirror 214 that transmits only the components LR and LB are incident. First to second total reflection mirrors 201 that reflect all components
~ 202. 230 shown in FIG. 3 is UV
-IR filter. 240 is a cold mirror.

The component LG transmitted through the first dichroic mirror 211 and the second dichroic mirror 212 is incident on the liquid crystal panel 31G on which an image corresponding to the component LG is displayed. The liquid crystal panel 31R on which an image corresponding to the component LR is displayed has the first dichroic mirror 21.
The component LR selectively reflected by 1 and reflected by the first total reflection mirror 201 is incident. Further, the component LB which is transmitted through the first dichroic mirror 211 and selectively reflected by the second dichroic mirror 212 is incident on the liquid crystal panel 31B on which an image corresponding to the component LB is displayed.

The component LB transmitted through the liquid crystal panel 31B and the component LR transmitted through the liquid crystal panel 31R are incident on the third dichroic mirror 213. The component LG transmitted through the liquid crystal panel 31G is incident on the fourth dichroic mirror 214 via the second total reflection mirror 202. This 4th
Since the components LR and LB incident on the third dichroic mirror 213 are also incident on the dichroic mirror 214 of FIG. It is projected onto the screen via system 40.

The liquid crystal panel will be described below by taking the liquid crystal panel 31R as an example. As shown in FIG. 4, the liquid crystal panel 31R includes a liquid crystal cell 311R in which a liquid crystal 315 is enclosed in two glass substrates 316, and a front side of the liquid crystal cell 311R (light source 10).
Side), a condenser lens 312R and an incident side polarization plate 313R, and an emission side polarization plate 314R provided on the rear side of the liquid crystal cell 311R. A predetermined gap is provided between the liquid crystal cell 311R, the incident side polarization plate 313R, and the condenser lens 312R so that the cooling air from the cooling fan flows. On the other hand, the emission side polarization plate 314R is provided in close contact with the liquid crystal cell 311R. Further, the incident-side polarization plate 313R and the emission-side polarization plate 314R are mixed with an additive that does not transmit incident ultraviolet rays.

[0007]

However, the conventional projection type image display device described above has the following problems. In the conventional projection-type image display device, since the transmittance of the component LB among the components LR, LG, and LB included in the light source light L decreases, the white balance tends to be biased toward the component LG side, and a natural color is obtained. Difficult to reproduce. The reason why the transmittance of the component LB is low is that the polarizing plate does not transmit ultraviolet rays.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide a projection-type image display device which is excellent in white balance and can reproduce natural colors.

[0009]

A projection type image display apparatus according to the present invention is a liquid crystal panel on which an image to be projected is displayed on a screen, a light source for projecting light source light on the liquid crystal panel, and a light source light from the light source. And a reflection system that guides the liquid crystal panel to the liquid crystal panel. Of the two polarizing plates, at least the emitting-side polarizing plate transmits ultraviolet light.

[0010]

EXAMPLE FIG. 1 is a graph for comparing the case where ultraviolet rays are transmitted and the case where ultraviolet rays are not transmitted, and FIG. 2 is a graph showing the relationship between white balance and black body radiation locus. It should be noted that parts that are substantially the same as those of the related art will be denoted by the same reference numerals in the following description.

The projection type image display apparatus according to the present embodiment has three liquid crystal panels 31R, 31G and 31B on which images to be projected on the screen are displayed, and the liquid crystal panels 31R, 31G and 31.
Light source 10 for projecting light source light L on B, and light source light L from light source 10
And a reflection system 20 for guiding the liquid crystal panels 31R, 31G, 31B.

The three liquid crystal panels 31R, 31G, 31B
The liquid crystal panel 31R, 31G, and 31B, which have the same structure, display an image corresponding to red as a representative of the liquid crystal panels 31R, 31G, and 31B.
An explanation will be given by taking R as an example. The structure of the liquid crystal panel 31R, that is, the liquid crystal cell 311R in which the liquid crystal 315 is enclosed, and the liquid crystal cell 31R
The liquid crystal panel 31R is similar to the liquid crystal panel 31R described in the section of the related art in that it has an incident side polarization plate 313R and an emission side polarization plate 314R provided on the incident side and the emission side of 1R, respectively.

However, the liquid crystal panel 31R is different from the conventional one in that the exit side polarizing plate 314R transmits ultraviolet rays. Assuming that the emission side polarizing plate 314R transmits ultraviolet rays, as shown in FIG.
The following components cannot be transmitted, but those that allow ultraviolet rays to transmit can transmit components of 330 nm or longer. Therefore, in the liquid crystal panel 31R used in the projection type image display device according to the present invention, the component LB of the light source light L is
The transmittance of the component on the short wave side corresponding to is improved. That is, the component LB used for displaying an image is increased as compared with the conventional case.

As described above, in order to obtain the emission-side polarization plate 314R that transmits ultraviolet rays, the emission-side polarization plate 31R does not include the additive that does not transmit ultraviolet rays, which has been conventionally mixed.
Mold 4R. As the incident side polarization plate 313R, one that does not transmit ultraviolet rays is used as in the conventional one.

On the other hand, the reflection system 20 includes two total reflection mirrors 201 to 202 and four dichroic mirrors 211 to 21.
4 and the source light L from the light source 10 as components LR, LG,
The components are decomposed into LBs and the respective components LR, LG, LB are made incident on the corresponding liquid crystal panels 31R, 31G, 31B, respectively. Since the three liquid crystal panels 31R, 31G, 31B and the reflection system 20 are arranged in the same manner as in the conventional projection type image display device, detailed description thereof will be omitted.

It is desirable that the white balance is on the black body radiation locus line shown by the solid line C in FIG. 2. However, as in the conventional case, an incident side polarizing plate and an emitting side polarizing plate that do not transmit ultraviolet rays are used, and a light source is used. When using a metal halide lamp as 10, the white balance is at point A. However, like the projection-type image display apparatus according to the present invention, if only the incident side polarization plate 313R does not transmit ultraviolet rays, that is, if only the emission side polarization plate transmits ultraviolet rays,
The white balance is displaced to a point B closer to the black body radiation locus than in the past, and a more natural color can be reproduced.

In the above-mentioned embodiment, the projection type image display device using the three liquid crystal panels 31R, 31G and 31B is taken as an example, but the present invention is not limited to this, and one projector is used. The present invention can also be applied to a so-called single-panel projection type image display device that uses only a liquid crystal panel.

Further, the same effect as described above can be obtained even if the incident side polarizing plate is provided with a coating that does not transmit ultraviolet rays and the emitting side polarizing plate is not provided with the coating.

[0019]

The projection type video display device according to the present invention includes a liquid crystal panel on which an image to be projected is displayed on a screen,
The liquid crystal panel includes a light source that projects light source light and a reflection system that guides the light source light from the light source to the liquid crystal panel. The liquid crystal panel includes a liquid crystal cell in which liquid crystal is sealed, and an incident side and an emitting side of the liquid crystal cell. The incident side polarization plate and the emission side polarization plate are provided on the side, and the incident side polarization plate is configured not to transmit incident ultraviolet rays, so that the component LB of the light source light is increased as compared with the conventional one. Then, the white balance approaches the ideal blackbody radiation locus line. This makes it possible to reproduce more natural colors than before.

[Brief description of drawings]

FIG. 1 is a graph for comparing a case where ultraviolet rays are transmitted and a case where ultraviolet rays are not transmitted.

FIG. 2 is a graph showing a relationship between a white balance and a black body radiation locus.

FIG. 3 is a schematic configuration diagram showing a configuration of a projection-type image display device.

FIG. 4 is a schematic configuration diagram showing a configuration of a liquid crystal panel.

[Explanation of symbols]

 10 Light source 20 Reflective system 31R, 31G, 31B Liquid crystal panel L Light source light

Claims (1)

Claim: What is claimed is: 1. A liquid crystal panel for displaying an image to be projected on a screen, a light source for projecting light source light onto the liquid crystal panel, and a reflection system for guiding the light source light from the light source to the liquid crystal panel. The liquid crystal panel comprises a liquid crystal cell in which liquid crystal is sealed, and an incident side polarizing plate and an emitting side polarizing plate respectively provided on the incident side and the emitting side of the liquid crystal cell. A projection-type image display device characterized in that at least the exit side polarizing plate transmits ultraviolet rays.