LIGHT BARRIER APPARATUS FOR MONITORING DOORWAYS

摘要

: In a light barrier apparatus for monitoring doorways to the left and to the right of a central post two light transmitter/receiver devices (11, 12) are mounted together with the associated electronic circuitry on a structural element to form a first unit. This unit is releasably secured to a base member which carries two deflecting mirrors (14, 15)and the electrical connection terminals. The unit can be removed from the base member (17) at right angles to a plane which includes the optical axes (11c, 12c) of the light transmitter/receiver devices (11, 12).