Browse Prior Art Database

Color Display Element using Nematic Liquid Crystals

IP.com Disclosure Number: IPCOM000076827D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Aviram, A: AUTHOR [+2]

Abstract

A display element which, when illuminated with parallel white light, transmits a selectable hue in the off-state and white in the on-state, is shown in Fig. 1. It consists of a thin, uniform layer of a nematic liquid in a homoeotropic texture, confined by glass plates coated with transparent conductors and sandwiched between crossed polarizers. The optic axis of the nematic liquid in the off-state is perpendicular to the large surfaces, and the propagation direction of the parallel light forms a small angle, alpha(0), with the optic axis direction. The polarization direction is 45 degrees to the plane of the drawing.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Color Display Element using Nematic Liquid Crystals

A display element which, when illuminated with parallel white light, transmits a selectable hue in the off-state and white in the on-state, is shown in Fig. 1. It consists of a thin, uniform layer of a nematic liquid in a homoeotropic texture, confined by glass plates coated with transparent conductors and sandwiched between crossed polarizers. The optic axis of the nematic liquid in the off-state is perpendicular to the large surfaces, and the propagation direction of the parallel light forms a small angle, alpha(0), with the optic axis direction. The polarization direction is 45 degrees to the plane of the drawing. When a slab of uniaxial material, such as the liquid crystal, is illuminated under these condition, those wavelengths whose integer multiplies equal to the retardation of the sample (R = m(lambda), where m = 0,1,2...) are extinguished and the transmitted light appears colored. First-order interference colors (m = 1) have bright hues, while high-order interference colors (m>6) degenerate into essentially white. The retardation, R, is determined by the thickness of the sample, the birefringence of the nematic liquid and on the angle, alpha. By appropriate choice of the thickness, and selecting alpha(0) in a range of conveniently small angles (say 5 degrees to 15 degrees) in the off-state any of the bright first-order interference colors are obtained.

When an electric field is applied (DC or preferably AC) the liquid crystal (with negative dielectric anisotropy) is deformed...