Apparatus for determining if duration of power failure exceeded predertermined limits

Abstract

In an electronics instrument, an external timer is used to time a predetermined brief period. If the timer has not yet expired when standby power is once again developed, then a controller will cause a real time clock to start timing, using the currently held time of day. If the timer has expired when standby power is once again developed, the controller will cause the time of day clock to indicate that its time is no longer accurate. Moreover, if the timer has expired, then the controller will not cause the receiver to be turned on. If the timer has not expired, then the controller will determine if the receiver was turned on when the AC power line failure occurred, and if so, the controller will cause the receiver to turn on. If the receiver was turned off when the AC power line failure occurred, then the controller will cause the receiver to remain in standby mode.

Description

technical field [0001] This invention relates to reset circuits for electronic equipment such as television receivers. Background technique [0002] Modern electronic receiver designs are increasingly employing digitally controlled chips (ie, integrated circuits) to control a variety of different functions such as image processing, picture-in-picture (PIP) processing, and audio processing. These chips are connected with the controller through the communication bus, and the controller can be a microprocessor, a microcomputer or a dedicated control integrated circuit. The controller is responsible for writing control parameters to the chip and reading status information from the chip. [0003] A television receiver may store data indicating whether the receiver is switched on or not. After an AC power line failure, the receiver can use this stored data to determine if the receiver was on at the time of the power failure, and to automatically turn it back on again. Unfortuna...

AI Technical Summary

Problems solved by technology

Unfortunately, it is not always desirable for the controller to bring the receiver back on after an AC power line failure, for example, if the power failure persists for several hours and the receiver is switched on in the middle of the night, perhaps at a loud volume setting. This is the case

[0004] Also, in a television receiver equipped with a real-time clock, the controller simply cannot determine how long the power interruption lasted

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