| 摘要 |
PURPOSE: An device and a method for controlling power of a video system are provided to automatically control the power of the video system using ultrasonic waves. CONSTITUTION: A device for controlling power of a video system includes an ultrasonic sensor(100), an oscillating/receiving circuit(102), a digital signal processor(104), and a controller(106). The ultrasonic sensor radiates ultrasonic waves at a low frequency and senses the ultrasonic waves. The oscillating/receiving circuit oscillates the ultrasonic sensor and receives an echo signal from the ultrasonic sensor. The digital signal processor digitalizes the received echo signal to calculate time of flight of the ultrasonic waves. The controller judges whether the time of flight is within a predetermined range and turn off the video system when the time of flight is within the predetermined range.
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