| 摘要 |
<p>PROXIMITY SWITCH A proximity switch is connected to close a circuit between a source and a load when a metal object is adjacent to a coil in the switch. The coil is part of an oscillator circuit that is selected to have its output damped below a selected amplitude when the metal object is close enough to the coil. The reduced amplitude of oscillation opens a capacitor shunting switch thereby permitting the capacitor to be charged. The charging of the capacitor to a selected level turns on an SCR to connect the load to the source through the SCR. A power storage circuit has a capacitor that is charged when the SCR is turned off to provide operating current for the circuits of the switch when it is not available because the SCR is turned on to shunt the current from the main power source. A circuit for controlling the proximity switch upon initial energization prevents spurious operation with a switching circuit that does not turn on until after a selected period of time after energization of the proximity switch from the main power source.</p> |
