| 摘要 |
<p>An inductive proximity switch contains an oscillator that generates an alternating magnetic field and which, when a trigger penetrates the alternating field, changes its oscillating state. An evaluation circuit uses the change in state to generate a switching signal to control a load switch. To achieve a proximity switch response distance that is as large as possible regardless of the trigger material and the ambient temperature, two sensing coils are located in the alternating field to detect the difference between voltages induced in them. The sensing coils are designed so that the alternating voltage differential becomes zero at a desired response distance. When the alternating voltage differential is zero at an input of oscillator amplifier, the oscillator abruptly changes its oscillating state. The change in oscillation state is detected by the evaluation circuit and converted into a binary switching signal for the load switch.</p> |
