JPH11237604A - LCD projector - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To convert a synthesizing system of G light into s-polarized light in all optical systems to p-polarized light, reduce loss light at the time of synthesizing by a dichroic prism, and improve the utilization rate of light from a light source. SOLUTION: The light of a light source 1 is converted to a dichroic filter 6.
The light is separated into B light and GR light by the dichroic filter 8.
To separate into G light and R light, B light, G light and R light for B color, G light
The LCDs 14B, 14G, and 14R for the colors R and R are illuminated, respectively, and the s-polarized G light from the LCD 14G is irradiated with a 1/2 phase difference plate 15.
Is converted to p-polarized light by the dichroic prism 16
It is combined with s-polarized B light and R light from CD14B and 14R.
The reflection characteristics of the s-lights of the dichroic filters 16BR and 16RR are shifted toward the G color, the reflection loss of the s-polarized B light and the R light is reduced, and the transmission loss of the p-polarized G light is reduced.

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 liquid crystal projector that synthesizes images using a dichroic prism, converts the polarization of green light incident on the dichroic prism, reduces loss of each color light, and uses light from a light source. For those that improve the rate.

[0002]

2. Description of the Related Art Red (R) light, green (G) light using a prism.
FIG. 3 shows an optical system of a liquid crystal projector that combines light and blue (B) light. That is,
The white light from the light source 1 is separated by the dichroic filter 6 into B light (transmission) and G light and R light (reflection), and the G light and R light are G light (reflection) by the dichroic filter 8.
Liquid crystal panel for blue light with B light
14B, the green liquid crystal panel 14G is illuminated with G light, and the red liquid crystal panel 14R is illuminated with R light.
The light of each color light-modulated by B, 14G and 14R respectively enters the dichroic prism 16, the B light is a dichroic filter 16BR, and the R light is a dichroic filter 16R.
Each light is reflected by RR, combined with G light, and the projection lens 17
Is projected on the screen via. By the way, the characteristics (50% transmission wavelength) of the dichroic filter have manufacturing variations. For example, BF (B light transmission) shown in FIG.
When the characteristic is shifted to the short wavelength side, it is indicated by a dotted line in FIG.
The BR (B light reflection) characteristic shifts in the direction of the arrow as shown by the solid line, a part of the B light spectrum to be reflected passes through the BR, the filled part becomes lossy light, and the RF (R light transmission) characteristic is reduced. When shifted to the long wavelength side, RR (R light reflection) indicated by a dotted line
The characteristic shifts in the direction of the arrow as shown by the solid line, a part of the R light to be reflected passes through the RR, and the filled part becomes lossy light, and the light utilization decreases. When the BF characteristic shifts to the long wavelength side and when the RF characteristic shifts to the short wavelength side, a loss occurs in the G light. When the inclination of the shoulder characteristic is large, for example, when the BF characteristic and the BR characteristic have the same 50% transmission wavelength, as shown in FIG. It becomes light.

[0003]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides an optical system comprising s-polarized light and converting a G light combining system (between a liquid crystal panel and a projection lens) into p-polarized light. Thus, the reflection characteristics (BR characteristics and RR characteristics) of the s-polarized B light and the R light of the dichroic prism are respectively shifted toward the G light to reduce the reflection loss, and at the same time, reduce the transmission loss of the p-polarized G light. It is an object of the present invention to improve the utilization rate of light from a light source.

[0004]

To achieve the above object, a liquid crystal projector according to the present invention comprises a light source,
In a three-panel liquid crystal projector device that includes a color separation optical system, an illumination optical system, a liquid crystal panel, an image synthesizing optical system, and a projection optical system and uses a dichroic prism for image synthesizing, the three liquid crystal panels output s-polarized light. At the same time, a 位相 phase difference plate is interposed between the liquid crystal panel for G color and the dichroic prism, the s-polarized light output from the liquid crystal panel for G color is converted to p-polarized light, and the R color is output by the dichroic prism. And the s-polarized light output from the liquid crystal panel for B color and the s-polarized light output from the liquid crystal panel for B color.

[0005] The 板 phase plate is mounted on the G light incident surface of the dichroic prism or the light emitting surface of the G color liquid crystal panel.

Alternatively, a 位相 retardation plate may be formed in a film shape and attached to the G light incident surface of the dichroic prism or the light emitting surface of the G color liquid crystal panel.

The s-polarized B light reflection characteristic and the R light reflection characteristic of the dichroic prism are shifted toward the G color, thereby reducing the reflection loss of the s-polarized B light and the R light while reducing the p-polarized G light. To reduce the transmission loss and improve the utilization of the light from the light source.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a configuration diagram of a main part of an optical system of an embodiment of a liquid crystal projector according to the present invention. In the figure, 1 is a light source that emits white light by a metal halide lamp or the like, 2 and 3 are lens arrays, 4 is a condenser lens, 5 is a mirror, 6 is a dichroic filter that transmits B light and reflects G and R light, 7 is mirror, 8 is G
A dichroic filter that reflects light and transmits R light, 9
Is a condenser lens, 10 is a mirror, 11 is a condenser lens, 12 is a mirror, 13B, 13G and 13R are condenser lenses, 14B is a liquid crystal panel for B light, 14G is a liquid crystal panel for G light, and 14R is R Liquid crystal panel for light, 15 is a 1/2 phase difference plate (shifts 90 ° phase), 16 is a dichroic prism, 16RR is a dichroic filter that reflects R light and transmits BG light, and 16BR reflects B light A dichroic filter that transmits G and R light, and 17 is a projection lens. The 1/2 phase difference plate 15 is mounted on the G light incident surface of the dichroic prism 16 or the light emitting surface of the G light liquid crystal panel 14G. Alternatively, the half-wave plate 15 is formed in a film shape, and the dichroic prism 16 is formed.
To the G light incident surface or the light emitting surface of the G light liquid crystal panel 14G.

The white light from the light source 1 is condensed by two sets of lens arrays 2 and 3 and a condenser lens 4, reflected by a mirror 5, separated by a dichroic filter 6 into B light and G / R light. The separated G / R light is separated by the dichroic filter 8 into G light and R light. The B light transmitted through the dichroic filter 6 is reflected by the mirror 7, irradiates the liquid crystal panel 14B for the B light via the condenser lens 13B, and the G light reflected by the dichroic filter 8 is collected by the condenser lens.
The R light that irradiates the liquid crystal panel 14G for G light through 13G and passes through the dichroic filter 8 passes through the condenser lens 9, mirror 10, condenser lens 11, mirror 12, and condenser lens 13R, and the liquid crystal for R light. Irradiate panel 14R. LCD panel 14
The s-polarized B light from B is reflected by the dichroic filter 16BR of the dichroic prism 16, and the liquid crystal panel 14R
The s-polarized R light is reflected by the dichroic filter 16RR of the dichroic prism 16, and the s-polarized G light from the liquid crystal panel 14G is converted into p-polarized light by the 1/2 phase difference plate 15, and the dichroic filter of the dichroic prism 16 is used. The light passes through 16BR and 16RR, whereby the three color lights of B, G and R are combined and projected on the screen via the projection lens 17.

As shown in FIG. 2, the dichroic filters 16BR (for reflecting B light) and 16RR (for reflecting R light) in the dichroic prism 16 change the reflection characteristics of s-polarized B light and R light toward G color, respectively. Stagger. Thereby, the reflection characteristic of the p-polarized B light, that is, the transmission characteristic on the short wavelength side of the p-polarized G light shifts to the short wavelength side, and the reflection characteristic of the p-polarized R light, that is, the long wavelength of the p-polarized G light Side shifts to the longer wavelength side. Therefore, the reflection loss of the s-polarized B light and the R light is reduced, and the transmission loss of the p-polarized G light is reduced, so that the utilization efficiency of the light source light is improved.

[0011]

As described above, according to the liquid crystal projector of the present invention, the combining system (from the liquid crystal panel to the projection lens) of the B light and the R light is composed of s-polarized light.
Since the system for synthesizing G light is converted into p-polarized light by a 位相 retardation plate, the B light of s-polarized light of the dichroic prism is
By shifting the reflection characteristics of the light and the R light toward the G light, respectively, it is possible to reduce the transmission loss of the p-polarized G light while reducing the reflection loss of the B light and the R light, thereby improving the utilization efficiency of the light source light. I do.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an optical system of an embodiment of a liquid crystal projector according to the present invention.

FIG. 2 is an example of a reflection characteristic of a dichroic filter in a dichroic prism.

FIG. 3 is a configuration diagram of a main part of an optical system of a conventional liquid crystal projector device.

FIG. 4 is an explanatory diagram of transmission / reflection characteristics and light loss of a dichroic filter.

[Explanation of symbols]

 Reference Signs List 1 light source 2, 3 lens array 4, 9, 11, 13B, 13G, 13R condenser lens 5, 7, 10, 12 mirror 6, 8, 16RR, 16BR dichroic filter 14R, 14G, 14B liquid crystal panel 15 1/2 Phase difference plate 16 Dichroic prism 17 Projection lens

Claims (6)

[Claims] 1. A three-panel liquid crystal projector device comprising a light source, a color separation optical system, an illumination optical system, a liquid crystal panel, an image synthesizing optical system, and a projection optical system, and using a dichroic prism for synthesizing an image. While outputting s-polarized light from the panel, inserting a １ ／ phase difference plate between the liquid crystal panel for green and the dichroic prism, converting the s-polarized output from the liquid crystal panel for green to p-polarized light, A liquid crystal projector device that combines a s-polarized light output from a liquid crystal panel for red and an s-polarized light output from a liquid crystal panel for blue by a dichroic prism. 2. The liquid crystal projector according to claim 1, wherein the half-wave plate is mounted on a green light incident surface of the dichroic prism. 3. The liquid crystal projector according to claim 1, wherein the half-wave plate is mounted on a light-emitting surface of the green liquid crystal panel. 4. The liquid crystal projector according to claim 1, wherein the half-wave plate is formed in a film shape and is attached to a green light incident surface of the dichroic prism. 5. The liquid crystal projector according to claim 1, wherein the １ ／ retardation plate is formed in a film shape, and is attached to a light emitting surface of the green liquid crystal panel. 6. The liquid crystal projector according to claim 1, wherein the blue light reflection characteristic and the red light reflection characteristic of the dichroic prism are shifted toward green, respectively.