| 摘要 |
A dust sensing apparatus (20) uses a transducer element (22, 24, 26) oscillating at a resonant frequency to detect changes in dust concentration. The transducer (22, 24, 26) is fabricated from a polymer material which oscillates when a voltage (64) is applied. The presence of dust affects the oscillation frequency. Dampening of the frequency by the dust presence changes the electrical resistance provided by the transducer. Electronic circuitry computes the level of dust by measuring and controlling the level of the AC signal (64) required to maintain the oscillation frequency by monitoring the resistance.
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