Nova Patents
EP0802685A2

Single plate liquid crystal colour display apparatus employing a diffraction grating

Abstract

White light (25) is input to light diffracting means (26') so composed as to have a structure including macro prisms combined with a lenticular structure and include diffraction gratings at a microscopic level. As the height (h(x)) of unit steps of said diffraction grating (27') is modulated at every period of arranged pixels, the output diffracted light is decomposed into three primary colors (R, G and B), and guided with highly accurate matching to the three respective primary color pixels (2) of a liquid crystal panel means (1). In the pitch modulation type diffraction grating of the prior art, it was basically impossible to avoid the defect that the converged positions of a red light ray (R) and a blue light ray (B) deviate about 30%. In contrast, according to the arrangement of this invention, it becomes possible to eliminate the deviation of the converged positions of not only the green light ray but the red light ray (R) and the blue light ray (B), making it possible to provide a single plate type color liquid crystal display apparatus with high light utilization efficiency.

EP0802685A2, drawing sheet 1
Sheet 1 of 40

Term

Term ended

Projected expiry passed 10 April 2017, 9.5 years ago.

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10 claims: 1 independent, 9 dependent

  1. 1
    A single plate type color liquid crystal display apparatus having light source means (23), collimator means (23), and single plate type liquid crystal panel means (1), comprising:light diffracting means (27) arranged between said collimator means (23) and said single plate liquid crystal panel means (1);and three-position means,    wherein said light diffracting means (27) is, at a macroscopic level, in a three-dimensional unflat plate form with a macro periodic structural pitch and additionally has at least either a macro-prism shape or a macro lenticular shape, and also includes a multistepped diffraction gratings (27) at a microscopic level, wherein the macro periodic pitch is larger than 53 µm, wherein input white light is, when it becomes diffraction output, decomposed into three primary color rays traveling in three different directions, wherein a separation angle ω between a red ray and a green ray in said three primary color rays is larger than 0.05 rad, wherein about L (L is an integer out of 1, 2 and 3) times a specific optical wavelength λ 0 is selected for at least the principal ray an effective unit optical path difference at a unit step of said multi-stepped diffraction grating (27), wherein an array pitch projection P of said unit step in the direction at right angles with an advancing direction of said green output ray is arranged so as to be substantially equal to a value obtained by dividing about L times a red-green wavelength difference (about 80 nm) by said red-green separation angle ω, more specifically, 80L nm/ω, and wherein said three primary color rays (R, G and B) as diffraction output, traveling in three different directions are converged to specified three color positions.