The invention relates to a fire detector having a fire sensor device for detecting a fire and for outputting a fire signal, having an environmental sensor device for detecting bodies in the environment of the fire detector and for outputting an environmental signal, and having a control device which sets a normal state and an alarm state of the fire detector on the basis of the fire signal. The invention also relates to a method for controlling the fire detector.
Fire detectors are used in private facilities, public areas or industrial environments in order to detect a fire in an environment in good time and to output an alarm. In conventional designs, fire detectors comprise a housing with an integrated sensor system which is designed to detect characteristic fire parameters. Since smoke or heat usually collects in the ceiling area of a room, it is conventional to position the fire detectors on the ceiling.
In order to ensure functionality of the fire detector, it must be set up in such a manner that it is not covered and is at a distance from objects in the environment. For example, relevant application standards, for example DIN VBE 0833-2 or DIN 14676, require fire detectors to be positioned in such a manner that no objects which could impair a proper method of operation are present within 50 cm of the detectors.
In principle, it is necessary to regularly perform tests in which a check is carried out in order to determine whether the environment of the fire detectors meets the requirements. However, when fire detectors are used in private households for example, it cannot be reliably assumed that such a test is actually carried out.
The document DE 10 2009 047 531 A1, which is probably the closest prior art, describes a smoke detector with ultrasonic antimasking, the smoke detector having, in addition to a smoke detection sensor, at least one ultrasonic sensor which is arranged in such a manner that it emits ultrasonic signals at least to the side and in a manner facing away from the ceiling or wall and can receive reflected ultrasonic signals and, in this manner, can check whether the environment is free of objects.