| 摘要 |
A U-shaped channel is mounted on the elevator car. A solid vane is mounted on the shaft wall near each floor. As the car approaches each floor the vane passes between the walls of the U-shaped column. A plurality of photo transmitter-receivers are mounted on the channel. The receivers on one wall and the transmitters on the opposite wall. As the vane passes between the walls, it obscures or occludes the light from the transmitters and the receivers are successively turned on and off in an arrangement indicative of the distance to the floor level.
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