Color variation in a passively illuminated display using fluorescent

Abstract

A light source, which has a time varying chromatic output, back lights or front lights a plurality of liquid crystal displays disposed in a desired arrangement. Two different colors can be produced at two different times by using a fluorescent light as the light source. The fluorescent light is a sealed tube having a high vacuum with an insert gas therein for energization of the gas and a low pressure mercury vapor. The tube has a coating on the inner surface of the tube of at least one phosphor. Energization of the inert gas causes the low pressure mercury vapor to arc to produce light of a first color during a first time period with the light of the second color being produced solely from the phosphor coating upon the gas being deenergized during the second time period. Each of the liquid crystal displays can be activated during the first time period, the second time period, both time periods, or remain inactivated during both time periods. This selective activation or inactivation of each liquid crystal display produces displayed information in the first color, the second color, or both colors. By forming the coating of a mixture of two phosphors with substantially different persistence times, a second color is produced during the second time period from the phosphor mixture, and a third color is produced during a third time period after the second time period solely from the phosphor having the longer persistence time.