JP2940778B2 - LCD projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector, and more particularly to a three-panel liquid crystal projector.

[0002]

2. Description of the Related Art Conventionally, in a three-panel liquid crystal projector,
The light from the light source is collimated by a reflecting mirror, and then separated into three primary colors by a dichroic mirror for B and a dichroic mirror for G, which are optical means for color separation. And
Each primary color light is condensed by each condensing lens and irradiated to each liquid crystal panel. In each liquid crystal panel, the light is modulated in accordance with the video signal, and then combined by a dichroic mirror for B and a dichroic mirror for G, which are optical means for color combination. Then, the combined light is enlarged and projected on a screen via a projection lens.

However, when the size of the liquid crystal panel is reduced for the purpose of reducing the size of the liquid crystal projector, the following disadvantages have been encountered.

[0004]

When the size of the liquid crystal panel is reduced, a part of the light beam is emitted outside the effective display area of the liquid crystal panel unless the light beam width of the light source is reduced, in other words, unless the light source is reduced in size. And a loss of light quantity occurs. In order to solve this, it is conceivable to change the curved surface of the reflecting mirror so that the light beam is made non-parallel so that the light beam irradiates the effective display area of the liquid crystal panel. However, in this case, a large amount of light is condensed at the center of the small liquid crystal panel, and heat or the like is generated at the center of the liquid crystal panel or the polarizing plate, and the projected image projected on the screen is deteriorated. Has disadvantages.

Accordingly, the present invention has been made in view of the above-mentioned drawbacks, and has as its object to obtain a liquid crystal projector with high illuminance even if a small liquid crystal panel is used.

[0006]

According to the present invention, there is provided a light source comprising a metal halide lamp or the like, a reflecting mirror for collimating a light beam from the light source, a condenser lens for condensing the collimated light beam, A liquid crystal panel that performs light modulation by receiving the light flux from the light source; and a projection lens that expands and projects light transmitted through the liquid crystal panel. A liquid crystal projector comprising means for making an incident angle and an outgoing angle parallel.

The present invention is also a liquid crystal projector characterized in that the central part of the surface of the condenser lens on the liquid crystal panel side is flat.

The present invention is also a liquid crystal projector, wherein the central part of the condenser lens is hollow.

[0009]

According to the present invention, as described above, of the light from the light source, the light applied to the central portion of the condenser lens is applied to the liquid crystal panel as parallel light without being collected. The light applied to the periphery of the condenser lens is applied to the effective display area of the condensed liquid crystal panel.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal projector according to the present invention will be described below with reference to FIGS.

FIG. 1 is a view for explaining light condensing by a condensing lens used in the liquid crystal projector of the present invention, FIG. 2 is an optical block diagram of the liquid crystal projector of the present invention, and FIG. FIG. 4 is an optical block diagram of a liquid crystal projector using a first condenser lens, and FIG. 4 is an optical block diagram of a liquid crystal projector using a second condenser lens.

In FIG. 1, a light beam from a light source 1 is converted into a parallel light by a reflecting mirror 2 and is incident on a condenser lens 4 via an infrared / ultraviolet cut filter 3. Condensing lens 4
Then, the above-mentioned parallel light is converged toward the effective display area of the liquid crystal panel 7. Here, the condensing lens 4 includes a flat portion 4a having a flat surface at a central portion and a portion facing the effective display area of the liquid crystal panel 7, and a curved surface portion 4b having a curved surface for condensing light at an outer peripheral portion thereof. It is composed of

With such a configuration, the flat portion 4
The light flux 10a passing through the liquid crystal panel 7 remains parallel light.
The light flux 10b passing through the curved surface portion 4b while irradiating the effective display area is focused toward the effective display area of the liquid crystal panel 7.

The infrared / ultraviolet cut filter 3 can be eliminated by coating the condenser lens 4 with infrared / ultraviolet rays.

Next, a specific embodiment of the liquid crystal projector of the present invention will be described with reference to FIG.

In FIG. 2, a light beam from a light source 1 is collimated by a reflecting mirror 2 and is incident on a condenser lens 4 via an infrared / ultraviolet cut filter 3. Condensing lens 4
Is composed of the flat portion 4a and the curved surface portion 4b as described above. The light beam passing through the flat portion 4a is incident on the effective display area of the liquid crystal panel 7 described later as parallel light, The light beam passing through 4b is collected toward the effective display area of the liquid crystal panel.

Each light beam that has passed through the condenser lens 4 is incident on a dichroic mirror 5B for separating blue light, the blue light beam is separated, and this blue light beam is reflected by a first reflection mirror 6a, and the liquid crystal panel for blue light is used. 7B. The light beam that has passed through the dichroic mirror 5B is incident on the dichroic mirror 5G, where the green light beam is separated, and this green light beam is incident on the green liquid crystal panel 7G. The light beam that has passed through the dichroic mirror 5G becomes a light beam of only the red component, and this red light beam is incident on the liquid crystal panel for red 7R. Each liquid crystal panel 7B,
In 7G and 7R, light is modulated based on the video signal, and the modulated primary color light beams are transmitted.

The modulated light flux is combined with the blue light flux and the green light flux by the dichroic mirror 8B, and the combined light flux is emitted to the dichroic mirror 8R.

On the other hand, the red light flux modulated by the liquid crystal panel 7R is reflected by the reflection mirror 6b and then emitted to the dichroic mirror 8R. In the dichroic mirror 8R, a red light beam is further combined with the combined light beam described above.
The image is enlarged and displayed on a screen (not shown) via the projection lens 9.

Next, the structure of the condenser lens used in the liquid crystal projector of the present invention is shown in FIGS.

In FIG. 3, the condensing lens 4 has a flat portion 4a having a flat surface at a center portion and a portion facing the effective display area of the liquid crystal panel 7, and a curved surface for condensing light at an outer peripheral portion thereof. And a curved surface portion 4b.

In FIG. 4, the condensing lens 4 has an opening 4c having an opening at a central portion and a portion facing the effective display area of the liquid crystal panel, and a curved surface for condensing light at an outer peripheral portion thereof. And a curved surface portion 4b.

The central portion of the condenser lens 4 is not limited to the above-described embodiment, and may have any configuration as long as the refractive index of the light beam is 0 degrees.

[0024]

According to the present invention, the conventional light source can be used even when a small liquid crystal panel is used, and a large number of light sources can be provided at the center of the effective display area of the liquid crystal panel. A bright projection image can be provided without condensing a light beam.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining light focusing by a focusing lens used in a liquid crystal projector of the present invention.

FIG. 2 is an optical block diagram of the liquid crystal projector of the present invention.

FIG. 3 is an optical block diagram of a liquid crystal projector using a first condenser lens.

FIG. 4 is an optical block diagram of a liquid crystal projector using a second condenser lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Reflecting mirror 3 Infrared / ultraviolet cut filter 4 Condensing lens 4a Flat part 4b Curved surface part 4c Opening 5B Blue dichroic mirror 5G Green dichroic mirror 6a Reflecting mirror 6b Reflecting mirror 7B Blue liquid crystal panel 7G Green liquid crystal panel 7R Liquid crystal panel for red 8B Dichroic mirror for blue 8R Dichroic mirror for red 9 Projection lens 10a Light flux passing through the flat part of the condenser lens 10b Light flux passing through the curved part of the condenser lens

Claims (3)

(57) [Claims] 1. A light source such as a metal halide lamp, a reflecting mirror for collimating a light beam from the light source, a condenser lens for condensing the collimated light beam, and receiving the light beam from the light source. A liquid crystal panel that performs light modulation, and a projection lens that enlarges and projects light transmitted through the liquid crystal panel. The light incident angle and the light output angle are parallel to the central portion of the liquid crystal panel side surface of the condenser lens. A liquid crystal projector characterized by comprising means. 2. The liquid crystal projector according to claim 1, wherein a central portion of the surface of the condenser lens on the liquid crystal panel side is flat. 3. The liquid crystal projector according to claim 1, wherein a central portion of the condenser lens is hollow.