Patent ID: 6462805
Filing Date: 2002-10-08
Classification: G02F

Abstract:
A direct-view liquid crystal display (LCD) operative in a reflective mode, comprising:a front substantially transparent substrate; a rear substrate; a controllable cholesteric liquid crystal (CLC) disposed between said front and rear substrates and having a characteristic wavelength in the non-visible spectrum, portions of said controllable CLC selectively exhibiting a planar state or a focal-conic state, said portions of said CLC in said planar state appearing dark to an observer of said LCD and said portions of said CLC in said focal-conic state appearing bright to an observer of said LCD; a mirror disposed proximate said rear of said LCD; and a circular or elliptical polarizer disposed proximate said front of said LCD, said circular or elliptical polarizer operative to circularly or elliptically polarize visible light incident on said front of said LCD, wherein: i) said portions of said CLC in said planar state allow the transmission of substantially all of said circularly- or elliptically-polarized visible light, which is substantially reflected from said mirror and back through said CLC; said reflected visible light having a handedness opposite to that of, and thereby blocked by, said circular or elliptical polarizer, whereby said portions of said CLC in said planar state appear dark to an observer of said LCD; and ii) said portions of said CLC in said focal-conic state at least partially depolarize said circularly- or elliptically-polarized visible light prior and subsequent to being reflected by said mirror; a portion of said partially-depolarized visible light having a circular or elliptical polarization of the same handedness as, and thus transmittable through, said circular or elliptical polarizer, whereby said portions of said CLC in said focal-conic state appear bright to an observer of said LCD.