Science Applications Incorporated Corporation

William J Coates, Jr

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 of the presentation of the light emitting display; and is capable of retaining display information upon the interruption of a light sustaining signal or the electrical power as a result of an accumulation and retention of electrical charge across the display medium. The apparatus comprising a repetition means for generating a repetition pulse train signal having a controllable frequency and duty cycle; an indication means for generating a retention signal that identifies when the light emitting display is capable of retaining display information; a synchronization means coupled to said repetition means and to said indication means for generating a gating signal which is synchronized with the retention signal and the repetition pulse train signal; and stopping means coupled to said synchronization means for interrupting the system clock in synchronization with the gating signal. Variations of this invention include circuitry which generates a control system clock signal by clock pulse train generator and modified stopping means. Other variations enable the light emitting display to be turned off over extended periods of time.

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San Diego, CA, United States of America

William J Coates, Jr