Patent ID: 6130489
Filing Date: 2000-10-10
Classification: H03K

Abstract:
An inductive proximity switch comprising:a coil;means for supplying the coil with periodic transmitting current pulses; andmeans for processing the signals which correspond to voltages induced after the end of a transmitting current pulse in said coil by the decaying current which previously flows in the detected body due to the voltage induced therein by the transmitting current pulse, whereinsaid supply means are adapted to supply said coil (11) with transmitting current pulses whose direction alternates periodically, the current flow pattern being such thatin the first half of a period (T21), the transmitting current delivered to said coil (11) by said supply means flows in a first direction and substantially only during a first interval (T11) which is shorter than one half of the period (T21) of the transmitted pulses, said transmitted current subsequently decays during a time interval (T11'), and is negligibly small during the remaining time (T12-T11') of the first half of the period, andin the second half of the period (T21) the transmitting current delivered to said coil (11) by said supply means flows in a direction opposite to the first one and substantially only during a second interval (T13) which is shorter than one half of the period (T21) of the transmitted pulses, said transmitted current subsequently decays during a time interval (T13'), and is negligibly small during the remaining time (T14-T13') of the second half of the period.