Standby system for video display

• US 4,641,191 A
• Filed: 12/07/1983
• Issued: 02/03/1987
• Est. Priority Date: 12/07/1983
• Status: Expired due to Fees

• Current Assignee: Zenith Electronics Corporation (LG Corporation)
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: Sutton, Leroy
• Primary Examiner(s): Chin, Tommy P.
• Application Number:
  US06/559,163
• Time in Patent Office: 1,154 Days
• Field of Search: 358/168, 358/161, 358/190, 358/188, 358/174, 358/83, 358/93, 358/105, 358/84, 358/110, 358/111, 358/112, 358/113, 307/116, 307/117, 340/554, 340/565, 340/566, 340/561, 340/568
• US Class Current: 348/687
• CPC Class Codes: H04N 5/57 Control of contrast or brightness

Abstract

A video display system is normally operated to produce a low brightness display on a CRT. Viewer sensing apparatus, including a transmitter and a receiver, senses the presence of a viewer by reflection of ultrasonic energy and operates a transistor having a time delay switch coupled in its load circuit for instantaneously supplying full power to the display system to produce a normal brightness display on the CRT. A transistor override circuit simulates closure of the time delay switch in response to an override signal for producing a full brightness display on the CRT independent of the time delay switch. The time delay switch maintains a full brightness display on the CRT for a predetermined time after the viewer leaves.

Claims

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.