JP2759718B2 - Projection type video display - Google Patents

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 having excellent white balance and capable of reproducing natural colors.

[0002]

2. Description of the Related Art FIG.
This will be described with reference to FIG. As this type of projection type image display apparatus, there is an apparatus using three liquid crystal panels 31R, 31G, and 31B of red, green, and blue (hereinafter, referred to as R, G, and B). Such a projection type video display apparatus includes a light source 10 for emitting light source light L, a reflection system 20 for decomposing the light source light L into components LR, LG, and LB, and an image to be enlarged and projected corresponding to R, G, and B. Liquid crystal panels 31R, 31G, 31B displayed on the screen
And a magnifying projection lens system 40 for superimposing the respective components LR, LG, LB transmitted through the three liquid crystal panels 31R, 31G, 31B and magnifying and projecting them on a screen (not shown).

[0003] 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. First and second total reflection mirrors 201 for reflecting all components
To 202. In addition, 230 shown in FIG.
-An IR filter. 240 is a cold mirror.

[0004] The component LG that has passed through the first dichroic mirror 211 and the second dichroic mirror 212 enters a 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 a first dichroic mirror 21.
The component LR selectively reflected at 1 and reflected by the first total reflection mirror 201 enters. Further, the component LB that has passed through the first dichroic mirror 211 and is selectively reflected by the second dichroic mirror 212 enters 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 a 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 fourth
Since the components LR and LB incident on the third dichroic mirror 213 are also incident on the dichroic mirror 214, the components LR, LG and LB are superimposed on the fourth dichroic mirror 214, and the enlarged projection lens Projected onto the screen via system 40.

Hereinafter, a liquid crystal panel will be described using 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 sealed 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 polarizing plate 313R provided on the (side), and an emission-side polarizing 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 polarizing plate 313R, and the condenser lens 312R so that cooling air from the cooling fan flows. On the other hand, the emission side polarizing plate 314R is provided in close contact with the liquid crystal cell 311R. Further, an additive is added to the incident-side polarizing plate 313R and the exit-side polarizing plate 314R so as not to transmit the incident ultraviolet light.

[0007]

However, the above-mentioned conventional projection type video display apparatus 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, and natural colors can be obtained. Difficult to reproduce. The transmittance of the component LB is low because the polarizing plate does not transmit ultraviolet light. But all
If a polarizing plate that transmits ultraviolet light is used,
Ultraviolet light is incident on the panel, resulting in deterioration of LCD panel quality
Occurs. This shortens the life of the projection display.
It is one of the factors that cause

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a projection-type image display device which has excellent white balance, can reproduce natural colors , and does not cause deterioration in quality of a liquid crystal panel. It is an object.

[0009]

According to the present invention, there is provided a projection-type image display apparatus comprising: a liquid crystal panel on which an image to be projected on a screen is displayed; a light source for projecting light source light onto the liquid crystal panel; And a reflection system for guiding the liquid crystal panel to the liquid crystal panel.The liquid crystal panel includes a liquid crystal cell in which liquid crystal is sealed, and an incident side polarizing plate and an emitting side polarizing plate provided on the incident side and the exit side of the liquid crystal cell, respectively. With incident side deviation
The light plate does not transmit ultraviolet light, and the exit-side polarizing plate does not transmit ultraviolet light.
To let it pass.

[0010]

FIG. 1 is a graph for comparing a case where ultraviolet light is transmitted and a case where ultraviolet light is not transmitted, and FIG. 2 is a graph showing a relationship between a white balance and a blackbody radiation locus. It is to be noted that parts and the like that are substantially the same as those of the related art are denoted by the same reference numerals and described.

The projection type video display apparatus according to the present embodiment has three liquid crystal panels 31R, 31G, 31B on which images to be projected on a screen are displayed, and these liquid crystal panels 31R, 31G, 31B.
A light source 10 for projecting the light source light L onto B, and a light source light L from the light source 10
To the liquid crystal panels 31R, 31G, and 31B.

The three liquid crystal panels 31R, 31G, 31B
Of the liquid crystal panels 31R, 31G, and 31B, a liquid crystal panel 31 on which an image corresponding to red is displayed.
This will be described with reference to R. The structure of the liquid crystal panel 31R, that is, the liquid crystal cell 311R in which the liquid crystal 315 is sealed, and the liquid crystal cell 31R
It is the same as the liquid crystal panel 31R described in the section of the prior art in that it has an incident side polarizing plate 313R and an emitting side polarizing plate 314R provided on the incident side and the exit side of the 1R, respectively.

However, the liquid crystal panel 31R differs from the conventional liquid crystal panel in that the exit side polarizing plate 314R transmits ultraviolet rays. Assuming that the exit-side polarizing plate 314R transmits ultraviolet light, as shown in FIG.
The following components cannot be transmitted, but those capable of transmitting ultraviolet light can transmit components of 330 nm or more. Therefore, in the liquid crystal panel 31R used in the projection display apparatus according to the present invention, the component LB of the light source light L
, The transmittance of the component on the short-wave side 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 polarizing plate 314R that transmits ultraviolet light, the emission-side polarization plate 31 can be obtained without mixing an additive that prevents the transmission of ultraviolet light, which was conventionally mixed.
Form 4R. Note that, as the incident side polarizing plate 313R, one that does not transmit ultraviolet light is used as in the conventional case.

On the other hand, the reflection system 20 comprises two total reflection mirrors 201 to 202 and four dichroic mirrors 211 to 21.
4 and the light source light L from the light source 10 is converted into components LR, LG,
The components are decomposed into LB, and the components LR, LG, LB are made to enter 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 a conventional projection type video display, detailed description will be omitted.

The white balance is desirably on the black-body radiation trajectory line shown by the solid line C in FIG. 2. However, as in the prior art, an incident-side polarizing plate that does not transmit ultraviolet light and an emitting-side polarizing plate are used, and a light source is used. When using a metal halide lamp as 10, the white balance is at the position of point A. However, as in the projection type image display device according to the present invention, if only the incident side polarizing plate 313R does not transmit ultraviolet rays, that is, if only the exit side polarizing plate transmits ultraviolet rays,
The white balance is shifted to a point B closer to the blackbody radiation locus than before, and a more natural color can be reproduced.

In the above-described embodiment, the projection type video display device using three liquid crystal panels 31R, 31G, 31B has been described as an example. However, the present invention is not limited to this, and the present invention is not limited thereto. The present invention can also be applied to a so-called single-panel type projection image display device using only a liquid crystal panel.

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

[0019]

According to the present invention, there is provided a projection type video display device, comprising: a liquid crystal panel on which an image to be projected on a screen is displayed;
The liquid crystal panel includes a light source for projecting light from the light source, and a reflection system for guiding the 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 entrance side and an emission side of the liquid crystal cell. The polarizing plate has an incident-side polarizing plate and an emitting-side polarizing plate provided on each side, and the incident-side polarizing plate transmits ultraviolet light.
The polarizing plate on the exit side transmits ultraviolet light.
ing. For this reason, the light source component LB
Increases, and the white balance approaches the ideal black body radiation trajectory line. This makes it possible to reproduce a more natural color than ever before. Also, the incident side polarizing plate transmits ultraviolet light.
UV light should not enter the LCD panel to prevent
No. As a result, quality deterioration of the liquid crystal panel caused by ultraviolet rays
No projection occurs and a longer lifespan projection image display device
be able to.

[Brief description of the drawings]

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

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

FIG. 3 is a schematic configuration diagram illustrating a configuration of a projection display apparatus.

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

[Explanation of symbols]

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

Claims (1)

(57) [Claims] A liquid crystal panel on which an image to be projected on a screen is displayed, a light source for projecting light source light onto the liquid crystal panel, and a reflection system for guiding 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 incident-side and the incident side polarizing plate respectively provided on the exit side and the exit side polarization plate of the liquid crystal cell, incident-side
The polarizing plate does not transmit ultraviolet light, and the exit side polarizing plate does not transmit ultraviolet light.
A projection type video display device characterized by transmitting light .