Standby system for video display

Claim 1

A video display system comprising: a CRT; video means including a video gain block for supplying information to said CRT for display; a source of B+ potential; a pair of resistors serially connected between said source of B+ potential and said gain block, said pair of resistors reducing the B+ potential available to said gain block sufficiently to operate said CRT at a low brightness level; sensing means, including an ultrasonic transmitter and an ultrasonic receiver, for detecting the presence of a movable object in a predetermined area adjacent said CRT by reflection of ultrasonic energy; switching means coupled to said sensing means for shorting out one of said resistors and enabling full operating potential to be applied to said video gain block for producing a high brightness display responsive to the presence of said movable object in said predetermined area; time delay means for maintaining said high brightness display for a time after removal of said movable object from said predetermined area; and a transistor having an output circuit coupled across said resistor for overriding said sensing means and producing a high brightness display independent of the presence of said movable object in said predetermined area whenever said transistor is energized.