Optical smoke detector with sensitivity adjustment

US4524281A · kind A · utility

Assignee

• Cerberus AG · CH

Inventors

• Jurg Muggli · Männedorf, CH
• Peter Gruber · Renningen, DE

Key dates

• Filing date: Nov 3, 1982
• Grant date: Jun 18, 1985
• Expiry date: Nov 3, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G08B17/113
• WIPO field: Control
• WIPO sector: Instruments

Abstract

A smoke detector is disclosed containing a radiation source and a radiation receiver arranged externally of a direct radiation region of the radiation source. In the presence of smoke or other combustion particles in the radiation region the radiation receiver is impinged by scattered radiation. The smoke detector contains optical elements which can be altered by external mechanical actuation, by means of which it is possible to alter in a predetermined manner an output signal of the radiation receiver. In this regard it is possible to either mechanically alter the solid angle which is so-to-speak viewed by the radiation receiver or the solid angle irradiated by the radiation source. The constriction of the active solid angle is preferably accomplished by a diaphragm or membrane displaceable along the radiation direction. Displacement of the diagram is preferably achieved in that, this diaphragm engages by means of dogs or detents in a cam groove, such as a helical-shaped groove of a cam disk, and by rotating the cam disk there can be achieved a defined displacement of the diaphragm.