| 摘要 |
<p>In a pushbutton switch one conductive plate is formed on a fixedly mounted printed circuit board. The other plate is comprised of a cantilever spring-mounted, movable, conductive, plate parallel with but spaced apart from the fixed plate. A pushbutton, constrained to move along a line perpendicular to the fixed and movable plates, is located opposite to the movable plate with the fixed plate in between. On the back side of the pushbutton is a small permanent magnet having a surface area approximately equal to that of the fixed and movable plates. Upon depression of the pushbutton the magnetic force of the magnet overcomes the spring force of the cantilever springs on the movable plate and snaps it into contact with the fixed plate. A stepwise change in impedance between the two conductive plates produced by depression of the pushbutton is detected providing an indication that the switch has been operated.</p> |
