Obscuration type smoke detector

US4185278A · kind A · utility

Assignee

• HF Systems, Incorporated · US

Inventors

• Willy Lintelmann · Old Saybrook, US
• Peter Frey · Heidenheim, DE

Key dates

• Filing date: Sep 22, 1977
• Grant date: Jan 22, 1980
• Expiry date: Sep 22, 1997

Classification

• Technology area (CPC G): Physics
• CPC primary: G08B29/24
• WIPO field: Control
• WIPO sector: Instruments

Abstract

Miniaturized smoke detectors, which operate on a light obscuration principle and may be either AC or battery operated, are both optically and electrically balanced whereby an unbalance resulting from the presence of smoke will trigger an alarm. The smoke detectors are characterized by a smoke chamber in which a light emitting diode and a pair of light detectors are installed in a manner which precludes relative movement therebetween. A splitter plate is also installed in the smoke chamber whereby both detectors are caused to see the same light flux density and one of the detectors, positioned in close physical proximity to the light source, acts as a reference signal source.