JPH085978A - Liquid crystal projector - Google Patents

Abstract

PURPOSE:To provide a liquid crystal projector which is simple in constitution and is capable of eliminating unnecessary light. CONSTITUTION:The white light from a light source 1 is made incident on a first green light separating dichroic mirror 4 via a UV/IR filter 3. The light of a wavelength 500 to 580nm including the first unnecessary light is reflected toward a second green light separating dichroic mirror 5 at this mirror 4 and the light of the wavelength exclusive thereof is transmitted to a red light separating dichroic mirror 6. The first unnecessary light is transmitted through the second green light separating dichroic mirror 5 and only the pure green light is made incident on a green light liquid crystal display part 8G via a green light condenser lens 7G. On the other hand, the light of a wavelength >=600nm is reflected in the red light separating dichroic mirror 6 and is made incident on a red light liquid crystal display part 8R via a red light condenser lens 7R. The remaining light of a wavelength <=500nm is made incident on a green light liquid crystal display part 8B via a blue light condenser lens 7B.

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-plate type liquid crystal projector using three liquid crystal panels.

[0002]

2. Description of the Related Art Conventionally, as shown in Japanese Patent Application Laid-Open No. 61-150487, a three-plate type liquid crystal projector using three liquid crystal panels has been generally used.

In this type of liquid crystal projector, the light emitted from the light source is divided into a green light separating dichroic mirror (reflecting light having a wavelength of 500 nm to 580 nm) and a red light separating dichroic mirror (reflecting light having a wavelength of 600 nm or more). Is separated into three primary colors of green light, red light, and blue light by two dichroic mirrors consisting of and one total reflection mirror, and light modulation is performed by a liquid crystal panel provided in the optical paths of green light, red light, and blue light, Each of the light-modulated three primary color lights was combined by two dichroic mirrors and one total reflection mirror, and the combined light was enlarged and projected on a screen through a projection lens.

[0004]

However, in the above configuration, in order to efficiently separate the three primary color lights from the light source, the green light separating dichroic mirror is 500 nm to 580 nm.
nm light is separated, and the red light separation dichroic mirror separates light having a wavelength of 600 nm or less, so pure green light (light having a wavelength of 520 nm to 580 nm) and red light (light having a wavelength of 600 nm or more) are separated. Could not get the light).

Therefore, as shown in FIG. 2, the green light liquid crystal panel receives the first unnecessary light (light having a wavelength of 500 nm to 520 nm), and the red light liquid crystal panel receives the second unnecessary light ( (Light having a wavelength of 580 nm to 600 nm) is incident, and these unnecessary lights cause heat deterioration and heat damage of the green light liquid crystal panel, the red light liquid crystal panel, and the polarizing plates arranged on both sides thereof. .

Particularly, the first unnecessary light has higher energy than the second unnecessary light, and the first unnecessary light is thermally deteriorated and damaged by the green light liquid crystal panel, the red light liquid crystal panel, and the polarizing plate. Was the main cause of

Further, in recent years, the brightness of liquid crystal projectors has been increased, and countermeasures against unnecessary light have become a problem for the increase in brightness.

The present invention has been made in view of the above problems, and an object thereof is to provide a liquid crystal projector capable of removing unnecessary light with a simple structure.

[0009]

According to the present invention, a light source for emitting white light, a first color separation means for separating green light from the white light from the light source, and a green color separated by the first color separation means are provided. Unnecessary light removing means for removing unnecessary light from the light; a green liquid crystal panel for optically modulating the green light from the unnecessary light removing means; and a second means for separating red light from the light transmitted through the first color separating means. A color separating means, a red liquid crystal panel for optically modulating the red light from the second color separating means, a blue liquid crystal panel for optically modulating the blue light transmitted through the second color separating means, and the green liquid crystal panel. First color synthesizing means for synthesizing the green light optically modulated by the red light and the red light optically modulated by the red liquid crystal panel, and the light synthesized by the first color synthesizing means and the blue liquid crystal panel Second color synthesizer that synthesizes modulated blue light When a liquid crystal projector, characterized in that it is composed of a projection lens for projecting the synthesized composite light by the second color combining means.

The present invention also includes a light source that emits white light,
A first color separation dichroic mirror that separates green light from white light from the light source, an unnecessary light removal unit that removes unnecessary light from the green light separated by the first color separation dichroic mirror, and the unnecessary light removal unit A green liquid crystal panel for optically modulating the green light from, a second color separation dichroic mirror for separating red light from the light transmitted through the first color separation dichroic mirror, and a red light from the second color separation dichroic mirror. A red liquid crystal panel for light modulation, a blue liquid crystal panel for light modulation of blue light transmitted through the second color separation dichroic mirror, and a green light and red liquid crystal panel for light modulation by the green liquid crystal panel. First color combining dichroic mirror for combining light-modulated red light, and light combined by the first color combining dichroic mirror A second color combining dichroic mirror for combining the blue light optically modulated by the blue liquid crystal panel, and a projection lens for projecting the combined light combined by the second color combining dichroic mirror. Is a liquid crystal projector.

[0011]

According to the present invention, with the above configuration, the white light emitted from the light source 1 is passed through the ultraviolet / infrared ray removing filter (hereinafter, abbreviated as UV / IR cut filter) to obtain the first green light separating dichroic. It is incident on the mirror.

In the first green light dichroic mirror, the first
Light having a wavelength of 500 nm to 580 nm including unnecessary light is reflected toward the second green light separating dichroic mirror, and light having other wavelengths is transmitted to the red light separating dichroic mirror.

In the second green light separation dichroic mirror,
The first unnecessary light is transmitted, and only pure green light enters the green light liquid crystal display unit through the green light condenser lens.

On the other hand, in the red light separating dichroic mirror, light having a wavelength of 600 nm or more is reflected and enters the red light liquid crystal display portion through the red light condenser lens, and the remaining light having a wavelength of 500 nm or less is blue light. The light is incident on the blue light liquid crystal display unit via the condenser lens.

Then, in each liquid crystal display section,
The primary color light is optically modulated according to a video signal.

The light-modulated green light and the red light are combined by a red-light combining dichroic mirror and then incident on a green-light combining dichroic mirror, and the light-modulated blue light is transmitted through a total reflection mirror to a blue-light combining dichroic. It is incident on the mirror.

Then, in the blue light combining dichroic mirror, the above-mentioned lights are combined, and the combined light is enlarged and projected on the screen through the projection lens.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid crystal projector of the present invention will be described below with reference to the drawings.

Here, FIG. 1 is an optical block diagram in this embodiment, FIG. 2 is an emission distribution diagram of a light source, and FIG. 3 is a spectral transmittance characteristic diagram of each dichroic mirror.

In FIG. 1, a light source 1 has a lamp 2 which emits white light such as a metal halide lamp. Then, the light source 1 emits white light having an emission distribution shown in FIG. 2, and after the white light is collimated, the ultraviolet ray / infrared ray removing filter 3 removes infrared rays and ultraviolet rays,
The light is incident on the first green light separation dichroic mirror 4.

The first green light separation dichroic mirror 4 is
It has the spectral transmittance characteristics shown in FIG. 3A, and the first green light separation dichroic mirror 4 includes the first unnecessary light 5
Light having a wavelength of 00 nm to 580 nm is reflected toward the second green light separating dichroic mirror 5, and light having other wavelengths is transmitted to the red light separating dichroic mirror 6.

The second green light separating dichroic mirror 5 has the spectral transmittance characteristic shown in FIG. 3B.
In the green light separating dichroic mirror 5, the first dichroic mirror 5 shown in FIG.
Unnecessary light is transmitted and pure green light (520nm ~ 580nm
nm) is incident on the green light liquid crystal display portion 8G through the green light condenser lens 7G.

Here, the green light liquid crystal display portion 8G comprises a green light liquid crystal panel 81G and first and second green light polarizing plates 82G and 83G arranged at the input and output of the green light liquid crystal panel 81G. First and second green light polarizing plates 82G, 8
The polarization direction of 3G has a polarization difference of 90 degrees according to the orientation of the green light liquid crystal panel 8G.

As a result, the first unnecessary light is the green light liquid crystal panel 81G, and the first and second green light polarization plates 82G and 83G.
Will not be incident on.

On the other hand, the red light separating dichroic mirror 6
Has the spectral transmittance characteristics shown in FIG. 3C, and the red light separation dichroic mirror 6 reflects light having a wavelength of 600 nm or more, and the reflected red light is red-lighted via the red light condenser lens 7R. While entering the optical liquid crystal display portion 8R, the remaining blue light having a wavelength of 500 nm or less enters the blue light liquid crystal display portion 8B via the blue light condenser lens 7B.

Here, the red light liquid crystal display portion 8R and the blue light liquid crystal display portion 8B have the same structure as the green light liquid crystal display portion 8G, and the red light display portion 8R includes a red light liquid crystal panel 81R and a red light liquid crystal panel 81R. It is composed of first and second red light polarization plates 82R and 83R arranged at the input and output of the light liquid crystal panel 81R, and the blue light liquid crystal display portion 8B also includes the blue light liquid crystal panel 81B and the blue light liquid crystal panel 81B. It is composed of first and second blue light polarizing plates 82B and 83B arranged at the input and output of the.

Further, the first and second red light polarizing plates 82R, 83
The polarization directions of R and the first and second blue light polarizing plates 82B and 83B have a polarization difference of 90 degrees in accordance with the orientation of the red light liquid crystal panel 81R or the blue light liquid crystal panel 81B.

Then, in each of the liquid crystal display sections 8G, 8R and 8B, respective three primary color lights are optically modulated according to a video signal from a video processing circuit (not shown).

Next, the green light and the red light optically modulated by the green light liquid crystal display portion 8G and the red light liquid crystal display portion 8R are shown in FIG. 3C.
After being synthesized by the green light synthesizing dichroic mirror 9 having the spectral transmittance characteristic shown in FIG. 1, the blue light which is incident on the blue light synthesizing dichroic mirror 10 and which is modulated by the blue light liquid crystal display unit 8 B is transmitted through the total reflection mirror 11. And is incident on the blue light synthesis dichroic mirror 10.

Then, the blue light synthesis dichroic mirror 1
0 has the spectral transmittance characteristic shown in FIG. 3B, and the blue light combining dichroic mirror 10 combines the above-mentioned lights, and the combined light is enlarged and projected on the screen via the projection lens 12.

In the above-described embodiment, the first unnecessary light having a relatively high energy component is removed, but another embodiment shown in FIG. 4 is used to remove the second unnecessary light.

The embodiment of FIG. 4 is different from the embodiment of FIG. 1 in that the arrangement of the green light liquid crystal display portion 8G and the red light liquid crystal display portion 8R is reversed, and accordingly, the first green light separation dichroic mirror, 2 Instead of the green light separating dichroic mirror, the red light separating dichroic mirror, and the green light combining dichroic mirror, a first red light separating dichroic mirror 61, a second red light separating dichroic mirror 51, a green light separating dichroic mirror 4, and a red light combining dichroic mirror 91.
Is the point using.

At this time, the first red light separation dichroic mirror 61 has a spectral transmittance characteristic of reflecting light having a wavelength of 580 nm or more, and the second red light separation dichroic mirror 51 has a wavelength of 600 nm or more. It has a spectral transmittance characteristic of reflecting the above light.

The green light separating dichroic mirror 4
Has a spectral transmittance characteristic of reflecting light having a wavelength of 520 nm to 580 nm.

Further, the red light combining dichroic mirror 91.
Has a spectral transmittance characteristic of reflecting light having a wavelength of 520 nm to 580 nm.

With this structure, the second unnecessary light can be removed.

[0037]

According to the present invention, the green light separated by the first green light separating dichroic mirror is separated again by the second green light separating dichroic mirror into pure green light.
Since the first unnecessary light does not enter the green light liquid crystal panel and the green light polarizing plate, it is possible to prevent thermal deterioration and heat damage of the green light liquid crystal panel and the green light polarizing plate.

The red light separated by the first red light separating dichroic mirror is again separated into pure red light by the second red light separating dichroic mirror to form a red light liquid crystal panel and a red light polarizing plate. The second unnecessary light does not enter,
It is possible to prevent the red light liquid crystal panel and the red light polarizing plate from being thermally deteriorated and damaged.

[Brief description of drawings]

FIG. 1 is an embodiment of a liquid crystal projector of the present invention.

FIG. 2 is a light emission distribution chart of a light source used in the liquid crystal projector of the present invention.

FIG. 3 is a spectral transmittance characteristic diagram of each dichroic mirror used in the liquid crystal projector of the present invention.

FIG. 4 is another embodiment of the liquid crystal projector of the present invention.

[Explanation of symbols]

 1 light source 2 lamp 3 UV / IR filter 4 first green light separation dichroic mirror 5 second green light separation dichroic mirror 6 red light separation dichroic mirror 7G green light condenser lens 7R red light condenser lens 7B blue light condenser lens 8G green light liquid crystal display section 8R red Optical liquid crystal display unit 8B Blue light liquid crystal display unit 9 Green light separation dichroic mirror 10 Blue light separation dichroic mirror 11 Total reflection mirror 12 Projection lens

Claims (4)

[Claims] 1. A light source that emits white light, a first color separation unit that separates the green light from the white light from the light source, and an unnecessary light that removes unnecessary light from the green light that is separated by the first color separation unit. A light removing unit, a green liquid crystal panel for optically modulating the green light from the unnecessary light removing unit, a second color separating unit for separating red light from the light transmitted through the first color separating unit, and the second A red liquid crystal panel that optically modulates the red light from the color separating means, a blue liquid crystal panel that optically modulates the blue light that has passed through the second color separating means, and a green light that is optically modulated by the green liquid crystal panel. And a first color synthesizing means for synthesizing the red light light-modulated by the red liquid crystal panel, the light synthesized by the first color synthesizing means, and the blue light light-modulated by the blue liquid crystal panel Second color synthesizing means,
A liquid crystal projector comprising a projection lens for projecting the combined light combined by the second color combining means. 2. A light source that emits white light, a first color separation dichroic mirror that separates green light from the white light from the light source, and unnecessary light is removed from the green light that is separated by the first color separation dichroic mirror. Means for removing unnecessary light,
A liquid crystal panel for green that optically modulates the green light from the unnecessary light removing means, a second color separation dichroic mirror that separates red light from the light transmitted through the first color separation dichroic mirror, and the second color separation dichroic A red liquid crystal panel for optically modulating red light from a mirror; a blue liquid crystal panel for optically modulating blue light transmitted through the second color separation dichroic mirror; and a green light optically modulated by the green liquid crystal panel. A first color combining dichroic mirror for combining the red light optically modulated by the red liquid crystal panel, a light combined by the first color combining dichroic mirror, and a blue light optically modulated by the blue liquid crystal panel. A second color combining dichroic mirror to be combined, and the second
A liquid crystal projector comprising a projection lens for projecting synthetic light combined by a color combining dichroic mirror. 3. The liquid crystal projector according to claim 1, wherein the unnecessary light removing unit is a dichroic mirror that reflects a wavelength of 520 nm or more. 4. The spectral transmittance characteristics of at least one of the color separation dichroic mirror and the color composition dichroic mirror are the same.
The described liquid crystal projector.