| 摘要 |
An inductive proximity switch includes a coil that is supplied with periodic transmitting current pulses. Signals which correspond to voltages induced in the coil after the end of a transmitting current pulse by the decaying current which previously flows in the detected body due to the voltage induced therein by the transmitting current pulse are then processed. The coil is supplied with transmitting current pulses whose direction alternates periodically. The current flow pattern is such that in the first half of a period of the current supplied to the coil, the transmitting current delivered to the coil flows in a first direction and substantially only during a first interval which is shorter than one half of the period of the transmitted pulses. The transmitted current subsequently decays during a time interval and is negligibly small during the remaining time of the first half of the period. In the second half of the period, the transmitting current delivered to the coil flows in a direction opposite to the first one and substantially only during a second interval which is shorter than one half of the period of the transmitted pulses. The transmitted current subsequently decays during a time interval, and is negligibly small during the remaining time of the second half of the period.
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