JPH0534818A - Projection system - Google Patents

Abstract

PURPOSE:To prevent a picture from being hard to see owing to the reflection of illumination light on a video display surface. CONSTITUTION:A lighting means 30 outputs illumination light consisting of only one linearly polarized light component and a video display device 1 outputs video light consisting of the other linearly polarized light component different from the linearly polarized light component of the illumination light; and a polarization plate means 21 which have its polarizing direction orthogonally to the linearly polarized light component of the illumination light is provided on the surface of the video display surface 20 where a video display is made by the video display device 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screening system comprising a video display device and indoor lighting means.

[0002]

2. Description of the Related Art A liquid crystal projector is known as a device for enjoying a large-screen image easily and at low cost. This liquid crystal projector is configured as shown as a liquid crystal projector 1 in FIG. 4, for example. 2 is a light source such as a halogen lamp, 3 is a cold reflector that transmits infrared rays and reflects visible light components, 4 is a cold filter that reflects infrared rays and transmits visible light components, 5 is a condenser lens, and 6 is an image A liquid crystal panel to which a drive signal based on the signal is applied and which functions as a light valve for each pixel, and 7 is a projection lens.

In this liquid crystal projector 1, of the light output from the halogen lamp 2, the cold reflector 3
By the action of the cold filter 4, only the visible light component is incident on the liquid crystal panel 6 via the condenser lens 5.

This liquid crystal panel 6 has three primary colors RGB (red,
(Green, blue) color filters and, for example, TN
Horizontal and vertical electrodes are arranged on the mode-transmissive liquid crystal to form pixels in a matrix. In each pixel corresponding to the RGB color filter, the TN liquid crystal is driven pixel by pixel based on the RGB video signal (transmission). Rate control), it is possible to obtain, as the output light of the liquid crystal panel, image light in which the light intensity is changed for each pixel portion, that is, color image light corresponding to the image signal. Then, the image light from the liquid crystal panel is enlarged and projected on the screen 10 by the projection lens 7. Reference numeral 11 indicates an indoor lighting device.

By the way, as is well known, light has two orthogonal planes of polarization (linearly polarized light) as shown in FIG. 5, which are generally a P-polarized component (hereinafter referred to as P-wave) and an S-polarized component. (Hereinafter referred to as S wave). Then, for example, the liquid crystal panel 6 used as a light valve in the liquid crystal display device 1 as described above uses only one polarization component of the incident light (P wave and S wave) and uses the other polarization component. It has a structure that eliminates it.

That is, in a liquid crystal panel for displaying an image, for example, as shown in FIG. 6, for example, only P waves are transmitted by a polarizing plate 6a, and horizontal and vertical electrodes 6b are arranged on a TN mode transmissive liquid crystal. Are introduced into the liquid crystal cell 6c in which matrix-shaped pixels are formed, while the S wave component does not pass through the polarizing plate 6a and is not used for liquid crystal display operation.

In the liquid crystal cell 6c (each pixel) to which the P-wave transmitted through the polarizing plate 6a is incident, the liquid crystal molecules 4 are arranged from the state shown in FIG. 6A to the state shown in FIG.
The transmittance is controlled by changing to the state of (b).

That is, in the case of FIG. 6A where the applied voltage is off, the P wave introduced by the optical activity of the liquid crystal molecules 6d is 90.
Twist and reach the polarizing plate 6e. The polarizing plate 6e is the polarizing plate 6
Since the light distribution axis direction is orthogonal to a, the light reaching the polarizing plate 6e is directly transmitted and is output as an S wave. Further, in the case of FIG. 6B in which the applied voltage is on, the optical rotatory power due to the liquid crystal molecules 6d is lost, and the incident P wave reaches the polarizing plate 6e as it is, and is blocked by the polarizing plate 6e.

Therefore, in the liquid crystal cell 3, if the applied voltage level is controlled for each pixel formed in a matrix on the basis of the image signal, image light can be obtained as an output of the liquid crystal panel. It should be noted that the above is the case of a so-called normally white type, and if the light distribution axis directions of the polarizing plates 1 and 5 are parallel, a normally black type in which light is blocked when the voltage is off is obtained.

[0010]

However, for example, in a liquid crystal display device using such a liquid crystal panel, as described above, only one polarization component of P wave or S wave of the light from the light source is used. Therefore, the light utilization efficiency is 1/2
Therefore, the brightness of the image projected on the screen 10 is not sufficient. Of course, this drawback is not limited to the liquid crystal projector as shown in FIG. 4, but also a rear projection type liquid crystal liquid crystal projector or a liquid crystal display device using the liquid crystal panel as a display surface (hereinafter,
The same applies to LCD monitors).

If the brightness of the image is not sufficient as described above, light generated in the room, such as illumination light from the indoor lighting device 11 and natural light incident from the window, may be reflected on the image display surface such as the screen 10. As a result, the image becomes very difficult to see, and therefore, there is a problem in that it is necessary to reduce the light amount of the indoor lighting device 11 and to close the curtain to make the room considerably dark at the time of the screening. In addition, this causes inconveniences such as the action of a person in the room being restricted and the movement being inconvenienced.

Further, in a CRT monitor or a CRT projector capable of obtaining a relatively high brightness image,
In some cases, the room light reflected on the image display surface causes the image to be difficult to see.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a screening system capable of displaying a good image without darkening the room. In a screening system including an indoor illumination unit and an image display device that displays an image on an image display surface, the illumination unit is configured to output only one linearly polarized light component as illumination light, and at least the image display device. , The image light of the other linearly polarized light component different from the one linearly polarized light component that is output as illumination light is output, and the image display surface on which the image is displayed by this image display device is The one linearly polarized light component output from the illuminating means is provided with a polarization plane means whose polarization directions are orthogonal to each other.

[0014]

In the illuminating device or the indoor illuminating means such as a window for taking in external light, only one polarization component is used as the illuminating light, and the polarization direction of the illuminating light is used as the polarizing plane means on the image display surface. By providing the polarizing plate in the direction orthogonal to the direction, it is possible to prevent the illumination light from being reflected on the image display surface.

[0015]

FIG. 1 shows an embodiment of the present invention.
Reference numeral 1 denotes a liquid crystal projector having the same configuration as that shown in FIG.
Is a screen on which an image is projected by the liquid crystal projector 1, and 30 is an indoor lighting device.

The image light output from the liquid crystal projector 1 is due to one of the linearly polarized light components as described above. Now, let us assume that this is due to the P wave component. Here, on the surface of the image projection surface of the screen 20 of the present embodiment, a polarizing plate 21 is arranged in close proximity (for example, attached). In this case, the polarizing surface of the polarizing plate 21 is a liquid crystal projector. 1 is substantially the same as the image light, that is, the direction in which the P wave, which is the polarization direction of the polarizing plate 6e on the emission side of the liquid crystal panel 6 in the liquid crystal projector 1, is transmitted. Further, the back surface side of the screen 20, that is, the reflection surface for reflecting the image light is a Fresnel surface 22 for increasing scattering in a direction orthogonal to the polarization surface of the polarizing plate 21.

Further, in the illuminating device 30, a polarizing plate 33 and a Fresnel concave lens 34 for illuminating the illumination light obtained by the light source 31 and the reflector 32 in the indoor direction are arranged. The polarization direction of the polarizing plate 33 is the screen 20.
In the direction orthogonal to the polarization plane of the polarizing plate 21, that is, in the present embodiment, the S-wave component is transmitted. The light transmitted through the polarizing plate 21 is diffused by the Fresnel concave lens 34 to provide indoor lighting.

In this embodiment, as shown in FIG. 2A, the P-wave image light (P _A ) output from the liquid crystal projector 1 is transmitted by the polarizing plate 21 with almost no attenuation (P _B ), And is hardly scattered by the Fresnel surface 22 and appears as reflected light (P _C ) (P _D ). That is, the attenuation of the reflected luminance is considerably small on the screen 20, and therefore the image is projected well.

On the other hand, as shown in FIG. 2B, the lighting device 3
The illumination light (S _A ) by the S wave output from
It is attenuated to less than half by 1 and is incident on the screen 20 (S _B ), is further scattered by the Fresnel surface 22 to reduce the reflection component (S _C ), and is transmitted through the polarizing plate 21 and appears as reflected light. The component (S _D ) is very small. That is, the room illumination light is hardly reflected on the screen 20.

Therefore, in the screening system of this embodiment, the image displayed on the screen 20 is not difficult to see due to the reflection of the room illumination light, that is, the image of the liquid crystal projector having a relatively low brightness. In particular, it will be possible to appreciate it sufficiently without making the room dark.
Also, since the room can be kept bright, there will be no inconvenience during the screening.

FIG. 3 shows another example of the configuration of the illuminating device 30 in the above embodiment. Illumination light obtained in the room direction by the light source 31 and the reflector 32 is first made incident on the polarization beam splitter 35 to generate a P wave. The S wave is separated. Then, the S wave reflected by the polarization beam splitter 35 is reflected by the mirror 36, guided to the Fresnel concave lens 34, and used as illumination light.

Further, the P-wave transmitted through the polarization beam splitter 35 is incident on the half-wave plate 37 to be converted into an S-wave, which is guided to the Fresnel concave lens 34 to be used as illumination light. Therefore, in this case, the illumination device 30 effectively uses the output of the P wave component from the light source 31 as the illumination light, and the illumination light is all the S wave component. Therefore, it can be suitably adopted as the screening system of the embodiment shown in FIG.

In the above embodiment, the illumination light is S wave,
The image light is P wave, and the P wave image light is projected well on the screen 20.
In the case of a liquid crystal projector that is a wave, the illumination light is a P wave and a polarizing plate 21 that is attached to the screen 20 is used.
Is the polarization direction for transmitting S waves, and the Fresnel surface 22
May be configured to scatter P waves.

Further, in the case of a room in which natural light enters from the window as the room illumination means, if a polarizing film is attached to the window, the illumination light can be either one of the S wave component and the P wave component. Therefore, the screening system can be configured by using the window as the illumination unit of the present embodiment.

By the way, the screening system of the present invention can be applied even when the image display device is other than the liquid crystal projector. Further, the image light does not necessarily have to be only one polarization component. Therefore, the video display device may be a CRT projector. In this case, one of the P wave component and the S wave component of the image light is not well reflected on the screen, and the reflected brightness is slightly lowered. However, as described above, the room illumination light hardly appears as reflected light. There is no particular problem.

Further, in the case of a CRT monitor, a liquid crystal monitor or the like which is not a projector, a polarizing plate having a polarization direction orthogonal to the illumination light may be arranged on the screen surface. In this case, of course, the image light has at least a polarization component orthogonal to the illumination light.

[0027]

As described above, the screening system of the present invention outputs the illumination light of only one linearly polarized light component from the illumination means, and the image display device outputs at least the other linearly polarized light component of the illumination light. The linearly polarized light component of the illumination light is output and the surface of the image display surface on which the image is displayed by the image display device has a polarization plane whose polarization direction is orthogonal to that of the linearly polarized light component of the illumination light. By providing the means, the reflection of the illumination light on the image display surface is almost eliminated, so that there is an effect that the image can be viewed sufficiently well under the illumination light. Also, by keeping the room bright, there is an advantage that the behavior of the person in the room will not be inconvenienced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a screening system of the present invention.

FIG. 2 is an explanatory diagram of the principle of the present embodiment.

FIG. 3 is an explanatory diagram of another example of the lighting device according to the present embodiment.

FIG. 4 is an explanatory diagram of a conventional screening system.

FIG. 5 is an explanatory diagram of a linear polarization component of light.

FIG. 6 is an operation explanatory diagram of a liquid crystal panel.

[Explanation of symbols]

 1 Liquid Crystal Projector 20 Screen 21 Polarizing Plate 30 Illuminating Device 33 Polarizing Plate 35 Polarizing Beam Splitter 36 Mirror 37 1/2 Wave Plate

Claims (1)

Claim: What is claimed is: 1. A screening system comprising illumination means and an image display device for displaying an image on an image display surface, wherein the illumination means outputs only one linearly polarized light component as illumination light. The image display device is configured to output image light of at least the other linearly polarized light component different from the one linearly polarized light component, and the image displayed by the image display device. The screening system, wherein the surface of the display surface is provided with a polarization plane means having a polarization direction orthogonal to one linearly polarized light component output from the illumination means.