| 摘要 |
Antennae located in the doors of an elevator car are in circuit with a balanced bridge detector coupled to an oscillator. Increased capacitance to ground produced by a person or object between the doors creates a bridge disbalance, which gives rise to the production of a bridge output signal whose level is proportional to the change in capacitance. Each time the car door opens at a floor, the signal level from the bridge obtained at an intermediate door position is stored as a reference indicative of the capacitance change resulting from dynamic environmental and structural factors. When the doors are fully open, the output from the bridge is compared with the stored signal level for detecting the additional capacitance created by a person or object between the doors and controlling door movement accordingly. |
