Improvements In Or Relating To A Light Curtain

摘要

A light curtain apparatus comprises a transmitter unit and a receiver unit Each of these comprises a casing (2), a lens unit (5) and a board (3) including a plurality of either light emitter diodes (10) or light receiver diodes (10A). The lens unit (5) comprises a plurality of lenses (15) each one aligned with a respective light emitter diode (10) or light receiver diode (10A). The components of each of the transmitter unit and the receiver unit are held in place by a window (7), located in an open face of each casing (2) by a lip (30). The operation of a light curtain may be checked by coding a light beam processor with a predetermined number, incrementing that number differently depending on the fault status of that beam and passing the incremented number to a next beam processor. The fault status of a curtain comprising a series of beam processors is determined from the value of the number output by the final beam processor of the series.