Light barrier having an optotransmitter and an optoreceiver

摘要

The invention relates to a light barrier, specifically a one-way light barrier, a reflection light barrier or a so-called forked coupler, in which locking devices are provided with the aid of which the optotransmitter can be arbitrarily blocked, and in which evaluation devices are provided by means of which in the event of blocking of the optotransmitter when there is no change in signal at the optoreceiver part which has previously been generating a received signal it is possible to generate an alarm signal so that it is finally possible to check the operational reliability of the light barrier. In this case, in an embodiment of the invention the use of at least two comparators also provides the possibility of signalling in good time an imminent failure of the light barrier, for example due to contamination of the transmitting optical system or of the receiving optical system.