A method and apparatus for modulating the perceptible intensity of the presentation of a light emitting display which light emitting display emits light by gas discharge and recombination of ions and free electrons of a display medium; includes a system clock, the interruption of which causes the interruption...http://www.google.de/patents/US4149111?utm_source=gb-gplus-sharePatent US4149111 - Method and apparatus for modulating the perceptible intensity of a light emitting display
