| 摘要 |
A closed-loop control for sensing the completion of popcorn popping in a microwave oven and automatically shutting down the oven. A microphone type sensor is acoustically coupled to the microwave oven cavity and provides an electrical signal to an amplifier and filter. The amplified and filtered signal is processed by a pop detector which includes an integrator and shut-down command generator responsive to a decreasing rate of popping to shut the oven off. The integrator provides a pre-pop timer function to maintain the oven on until popping commences. In an alternative sensor embodiment, a piezolelectric type sensor is used. In an alternative pop detector embodiment an adaptive threshold comparator which automatically adjusts pop detector operation to discriminate the popping signal from ambient noise present in the oven.
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