| 摘要 |
<p>A detector, for controlling automatic doors, comprises an A.C. generator connected to a transmitting aerial, and a spaced receiving aerial connected via a conductor, both of which are pref. encased in a polyester resin or in neoprene, to an electronic circuit which measures the A.C. potential induced on the receiving aerial and emits a control signal when something is present between the aerials.</p> |
