Browse Prior Art Database

Liquid Crystal Color Display

IP.com Disclosure Number: IPCOM000053026D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 3 page(s) / 87K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

A liquid crystal display is described in which white light is incident upon a diffraction grating. A selected color is then reflected out of the display through a transparent window slit having a position and size controlled by nematic fluid.

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 53% of the total text.

Page 1 of 3

Liquid Crystal Color Display

A liquid crystal display is described in which white light is incident upon a diffraction grating. A selected color is then reflected out of the display through a transparent window slit having a position and size controlled by nematic fluid.

When a nematic liquid crystal fluid is placed between electrodes, voltages on the order of 10 volts or less will cause the fluid to change from transparent to diffuse white in a fraction of a second, and return again about as quickly when the voltage is removed. Fig. 1 illustrates how this change in optical property can be used to fabricate a color display using a white light source.

A basic display unit cell comprises two cells 10, 12 of nematic liquid crystal fluid, a chirped diffraction grating 14 (the grating periodicity varies along the length), two transparent conductive electrodes 16, 18, a reflective conductive coating 20, an opaque coating 22, and cover plates 24, 26. When a voltage is applied to either of the two cells, only a portion 15 of that cell will turn from its transparent state to its diffuse state. As the voltage is increased, more of the liquid crystal will change to the diffuse state. By applying the proper voltages to the two liquid crystal cells, effectively an aperture or a slit is made to move up and down along the diffraction grating which follows the expression V(1) + V(2) - V(slit) = V(o). and is schematically depicted in Fig. 2. Incident white light 28 illuminates one-half of the basic cell. The grating diffracts the light, and the wavelength of light diffracted at t...