Process for monitoring the openings to an enclosed space

摘要

A process for monitoring an opening of an enclosed space by an IR alarm system, wherein: a measuring process is generated whereby a modulated IR beam is emitted by at least one IR emitting element of an optoelectronic unit in the form of a pulse and the beam reflected from marginal areas of the opening is detected as a measurement signal by at least one IR receiving element of the optoelectronic unit, with the directional characteristic of th IR beam being matched, by optical components in the path of the beam, to the opening being monitored; the measurement signal detected by the receiving element is compared with a mean value of the previous measurement signals, and a normal operating mode of the alarm system is initiated if there is an approximate correlation between the measurement signal and the mean value, or an alarm operating mode of the alarm system is initiated if there is a significant deviation between the measurement signal and the mean value; in the normal operating mode, the next measuring process is generated after a pause in time, during which the control unit, emitting element and receiving element are switched off; and, in the alarm operating mode, a number of measuring processes are generated in immediate succession and compared with criteria stored in the control module, and an alarm signal is tripped if the measurement signals from the measuring processes correspond with the stored criteria.