Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Reexamination Certificate
2000-01-19
2001-12-11
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
C359S634000, C353S033000
Reexamination Certificate
active
06330114
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention related to a color mixing apparatus for reflective displays using a total internal reflection (TIR) prism, and more particularly, to a color mixing apparatus for reflective displays in which the magnitude of prism angle in the TIR prism and the magnitude of an incident angle of each color light is adjusted to facilitate the design of a projection lens.
2. Description of the Related Art
A color mixing apparatus for reflective displays using a TIR prism mixes R, G and B color light using three TIR prisms, three reflective display devices and a color cube. The mixed color light is formed as an image on a screen via a projection lens. As the F number of the projection lens (focal distance/lens effective aperture) become larger, the projection lens can be more easily designed. That is, if the F number of the projection lens is large, the number of the lenses used for designing the projection lens is reduced, thereby making it easy to design a projection lens. Thus, in order to enlarge the F number of the projection lens, the magnitude of the off-axial angle should be reduced or a back focal length (BFL) should be shortened in a color mixing apparatus.
However, in the color mixing apparatus, if the magnitude of the off-axial angle becomes smaller, the BFL becomes longer, while if the BFL becomes shorter, the magnitude of the off-axial angle becomes greater. Thus, it is difficult to reduce both the magnitude of the off-axial angle and the BFL.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a color mixing apparatus for reflective displays in which the magnitude of a prism angle in the TIR prism and the magnitude of an incident angle of each color light are adjusted to facilitate the design of a projection lens.
To accomplish the above object of the present invention, there is provided a color mixing apparatus for reflective displays which forms an image on a screen, the color mixing apparatus comprising: reflective display devices for reflecting each of incident R, G and B color lights; total internal reflection (TIR) prisms for transmitting each of the incident R, G and B color lights so that the transmitted light proceeds to each of the reflective display devices and totally reflecting the R, G and B color light reflected from each of the reflective display devices; a color cube for mixing the R, G and B color light totally reflected from the TIR prisms; and a projection lens for transmitting the light mixed from the color cube and forming an image on a screen, wherein the magnitude of the prism angle is adjusted for each TIR prism and the magnitude of an incident angle of each color light incident to said each TIR is adjusted, thereby facilitating the design of said projection lens.
REFERENCES:
patent: 5420655 (1995-05-01), Shimizu
patent: 5604624 (1997-02-01), Magarill
patent: 6128055 (2000-10-01), Park
patent: 11-2780 (1999-01-01), None
patent: 0227636-A (2000-08-01), None
Park Joon-Chan
Song Kwon-Euy
Epps Georgia
Samsung Electronics Co,. Ltd.
Spector David N.
Sughrue & Mion, PLLC
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