Abstract: In this system for the securing of rooms, one or more transmitting elements emit suitably modulated light pulses into given regions or sectors which are produced by specially shaped optical components and/or by a special alignment of the transmitting elements and/or by the application of absorbent layers to an infrared filter which is located in front of the transmitting elements and receiving elements. One or more receiving elements receive the incident radiation. Changes in the radiation field with respect to intensity and/or speed of change of the intensity and/or phase are processed in subsequent evaluation logic circuitry. The room security system can also be combined into a larger unit with common evaluation logic.

Abstract: An area-security system comprises a transmitting/receiving strip arranged along one side of an area to be secured and a reflection strip arranged along the other side. The transmitting/receiving strip is divided into transmitting regions and receiving regions, the transmitting regions consisting of a plurality of transmitting elements which are arranged alongside of each other and which are combined in at least two groups, and the receiving regions also consisting of a plurality of receiving elements which are arranged alongside of each other and are also combined in at least two groups. Modulated light from the transmitting elements strikes the receiving regions after being reflected by the reflection strip. A control circuit determines association of different groups of receiving elements with the individual groups of transmitting elements. A multi-channel evaluation, under the synchronizing control of a control circuit, evaluates the signals on the basis of various factors.