Function test means of photoelectric smoke detector

Claim 1

A function testing means for a selfchecking photoelectric type smoke detector which comprises a light-emitting element (1) for detecting smoke, a light-receiving element (2) for detecting smoke located at a position out of direct reach of light from the light-emitting element (1) for detecting smoke, and an evaluation circuit which transmits a smoke detecting or an abnormal condition signal, respectively, to a fire control panel, characterized in that a light-receiving element (5) for supervision which receives light directly from the light-emitting element (1) for detecting smoke and which supervises the light-emitting state of the light-emitting element (1) for detecting smoke and a light-emitting element (4) for testing which radiates light corresponding to the received output of the light-receiving element (5) for supervision directly onto the light-receiving element (2) for detecting smoke are provided, whereby alternately a function test mode in which the light-emitting element (1) for detecting smoke and the light-emitting element (4) for testing emit simultaneously light to test the smoke detecting function, and a smoke detecting mode in which the light-emitting element (1) for detecting smoke alone emits light to detect smoke is created, and that discrimination of the function test and the detection of smoke is performed in parallel by discriminating whether the smoke detecting function is normal or not during the function test mode by checking whether the received light output of the light-receiving element (2) for detecting smoke is within a range in which no false alarm or alarm failure is'caused, and by discriminating whether smoke is present or not during the smoke detecting mode by checking whether the received light output of the light-receiving element (2) for detecting smoke is within a range in which the smoke detecting signal is produced.