Bistable electromagnetic light beam switch - has rotating arm with two rest positions one of which sets mirror in path of light beam

摘要

The optical switch is designed for use in situations where deflection of a light beam by an electrical signal is required. The device does not need a continuous supply of energising current but only when a change from one stable position to the other is made. A fixed magnetic core (2) has an energising coil (9) which defines the polarity of its pole faces (12,13,16). One end of the core is symmetrically forked into two branches. A pivoting arm (3) turns about an axis (7) on the line of symmetry (14) through the fixed magnet and carries a permanent magnet (4,5) on each end. The permanent magnets have opposite magnetic poles adjacent to the arm so that either one side of the arm or the other will be attracted by the energised electromagnet pole-face. The arm thus has two stable positions. A mirror (17) is fixed to one side of the arm so that a light beam (19) can be reflected from the source (18) to a receiver (20) when the arm is in the correct position. Several variations of this arrangement are described, including one where the arm has only one permanent magnet and pivots about one end instead of the centre.