Abstract: The invention relates to a method in an optically operated proximity switch. A transmitter means is used to transmit a beam in a direction into the environment. The detection zone on one hand and the background area on the other hand are monitored by receiving means. In addition, processing means are used in the method by which the output signals of the receiving means are compared to monitor the situation in the detection zone. An object is detected by the processing means when the output signal of the first receiver means monitoring the detection zones is changed in relation to the output signal of the second receiver means monitoring the background. When the said change is ended, the phase of detection of the object is ended and the output signal of the first receiver means is returned to a substantially original level.

Abstract: The invention relates to a method in an optically operated proximity switch, particularly for checking the working condition of the proximity switch. Accordingly to the method, the proximity switch is fitted with a control circuit which is switched on at certain intervals. The control circuit comprises, in addition to a coupling, a controlling receiver circuit and a controlling transmitter circuit, whereby the working condition of the transmitter and the receiver is checked. The proximity switch further comprises reflecting device, whereby the control pulse is reflected to the receiver.