JPH1164973A - Back projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve contrast by the blackness of a polarizing plate by arranging an incident-side polarizing plate between a light source and a liquid crystal panel and an emitting-side polarizing plate on the observer side of a screen. SOLUTION: This back projection type display device is constituted of a video projection device 10 arranged in a housing, a projection lens and a transmission type diffusion screen part 20. In the device 10, a metal halide lamp 2 functioning as a light source, the incident-side polarizing plate 5 and a liquid crystal panel 6 are arranged in this order. White light radiated from the lamp 2 is polarized by the plate 5, passes through the panel 6 and becomes a video being the polarized light components of the S polarized light of black display and the P polarized light of white display in a specified vibration direction. In the screen part 20, the emitting-side polarizing plate 23 through which only P wave presses is arranged on a side nearest to the observer side. A black sheet is used for the plate 23. Therefore, the P wave passes through the back surface of the screen part 20 and S wave is reflected on the back surface of the screen part 20, so that only the video light of a white display part is given to the observer side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection display device, and more particularly, to a rear projection side of a screen which receives a projection image from an image projection device, and directs an image light to an observer located in front of the screen. The present invention relates to a rear projection display device which emits light.

[0002]

2. Description of the Related Art FIG. 5 is a schematic configuration diagram showing a conventional rear projection display device.
A projection device 102 having a liquid crystal panel inside a housing 101, a projection lens 103, a reflection mirror 104,
105 and a transmission type diffusion screen 106. The projection image light from the projection device 102 is reflected by the reflection mirrors 104 and 105 via the projection lens 103, and the projection image light is incident on the rear side of the transmission type screen 106 and diffused and emitted from the front side of the screen 106. This allows the observer to view the video at the position in front of the screen 106.

[0003]

In the rear projection type display device using the liquid crystal panel described above, there is a problem that some amount of light is observed even in the front black display state, and the contrast is reduced. .

An object of the present invention is to provide a rear projection display device having the same contrast as that of a direct-view liquid crystal display device in order to solve the above-mentioned conventional problems.

[0005]

SUMMARY OF THE INVENTION A rear projection display device of the present invention enlarges image light from an image projection device having a light source and at least one liquid crystal panel by a projection lens to project and display the image light from the rear side of a screen. In the rear projection display device described above, an incident-side polarizing plate is disposed between the light source and the liquid crystal panel, and an output-side polarizing plate is disposed on the viewer side of the screen.

According to the above configuration, the exit side polarizing plate is the final surface on the viewer side, so that the contrast can be improved by the blackness of the polarizing plate.

It is preferable that the liquid crystal panel is modulated so that the black display section has an S wave and the white display section has a P wave.

Further, a polarizing mirror may be arranged on the projection lens side of the screen.

With the above configuration, the P wave is transmitted and the S wave is reflected on the back surface of the screen, and only the image light of the white display section is given to the observer side.
The contrast is improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a rear projection type liquid crystal device using a single-panel type liquid crystal panel according to an embodiment of the present invention.

The rear projection display device includes an image projection device 10, a projection lens, and a transmission type diffusion screen unit 20 arranged in a housing.

The projection apparatus 10 includes a reflector 1, a metal halide lamp 2 as a light source, a UV / IR filter 3, a condenser lens 4, an incident side polarizing plate 5,
The liquid crystal panel 6 is arranged in this order. The white light emitted from the metal halide lamp 2 is UV /
After being transmitted through the IR filter 3 and condensed by the condenser lens 4, it is polarized by the incident-side polarizing plate 5 and enters the liquid crystal panel 6. The liquid crystal panel 6 has a liquid crystal layer sandwiched between glass substrates, is polarized by the incident-side polarizing plate 5, and the light incident on the liquid crystal panel 6 is transmitted through the liquid crystal panel 6 so that the S-polarized light and the P-polarized light have specific vibration directions. It becomes image light due to the polarization component. In this embodiment, a vertical direction (P wave) is displayed in white as shown in FIG. 4 for a screen in which the polarization oscillation direction emitted from the liquid crystal panel is 4: 3 (see FIG. 4B). ), And the horizontal direction (S wave) is displayed in black (see FIG. 3A).

When color display is performed by the single-panel liquid crystal panel 6, a color filter is provided on the front surface of the liquid crystal panel 6. The color filter is composed of pixels for red (R) and green (G) formed in a matrix on the liquid crystal panel 6.
And a red light filter unit, a green light filter unit, and a blue filter unit respectively corresponding to the blue pixel and the blue (B) pixel. The white image light transmitted through the liquid crystal panel 6 is a color image light. Is converted to

The polarized light in a specific vibration direction emitted from the liquid crystal panel 6 is given to a projection lens 7. Projection lens 7
Are designed to enlarge and project the image light.

The screen section 20 of the present invention comprises an exit-side polarizing plate 23 through which a P-wave is transmitted on the observer-side surface of a transmission screen comprising a Fresnel lens plate 21 and a diffusion sheet 22 attached to the observer side. And a polarizing mirror 24 is attached to the projection lens 7 side.

That is, the output side polarizing plate 23 is connected to the screen unit 2.
For example, the output side polarizing plate 23, the diffusion sheet 22, and the Fresnel lens plate are arranged so that the polarizing mirror 24 is disposed at a position closest to the observer side and the polarizing mirror 24 is disposed farthest from the observer side. 21 and a polarizing mirror 24 in this order.

The surface of the output side polarizing plate 23 is subjected to non-glare treatment, and a black sheet is used for the polarizing plate 23 itself.

The image light emitted from the projection lens 7 reaches the screen section 20 by setting the white display section to P-wave and the black display section to S-wave in the optical path until reaching the screen section 20, as shown in FIGS.
As shown in (2), the P wave is transmitted and the S wave is reflected on the back surface of the screen unit 20, and only the image light of the white display unit is given to the observer, so that the contrast is improved. Further, since the output side polarizing plate 23 is the final surface on the observer side, the contrast is further improved by its blackness. Further, it is preferable to apply a surface treatment, such as reflection prevention, applied to a normal direct-view type liquid crystal panel to the emission-side polarizing plate 23.

In the above embodiment, the polarization mirror 24
In this configuration, the S-wave is transmitted, and the P-wave is reflected so that the image light of black display is not transmitted through the screen unit 20 reliably. However, the P-wave is transmitted through the incident surface of the Fresnel plate 21 and the S-wave is transmitted. Since there is a tendency to reflect light, the amount of light given to the observer from the output-side polarizing plate 23 during black display can be greatly reduced without providing the polarizing mirror 24, and the contrast can be improved.

[0020]

As described above, according to the present invention, the amount of video light for black display is not provided to the observer, and the contrast is improved. Further, since the output side polarizing plate is the final surface, the contrast is improved by its blackness.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing the configuration of a rear projection type video apparatus according to the present invention.

FIG. 2 is an exploded perspective view showing a configuration of a screen unit according to the present invention.

FIG. 3 is a plan view showing a configuration of a rear projection type video apparatus according to the present invention.

FIG. 4 shows a polarization component of a video signal according to the present invention;
Indicates an S wave in black display, and (b) indicates a P wave in white display.

FIG. 5 is a configuration diagram of a conventional rear projection display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reflector 2 Metal halide lamp 5 Incident side polarizing plate 6 Liquid crystal panel 7 Projection lens 20 Screen part 21 Fresnel lens plate 22 Diffusion sheet 23 Outgoing side polarizing plate 24 Polarizing mirror

Claims (3)

[Claims] 1. A rear projection display device for enlarging image light from an image projection device having a light source and at least one liquid crystal panel with a projection lens and projecting and displaying the image light from the rear side of a screen. A rear-projection display device, wherein an incident-side polarizing plate is disposed therebetween, and an output-side polarizing plate is disposed on the viewer side of the screen. 2. The rear projection display device according to claim 1, wherein the liquid crystal panel is modulated so that a black display section has an S wave and a white display section has a P wave. 3. The rear projection display device according to claim 2, wherein a polarizing mirror is arranged on the projection lens side of the screen.