Arrangement in order to prevent false alarms of a passive infrared motion alarm

US4307388A · kind A · utility

Assignee

• Heimann GmbH · DE

Inventors

• Gerhard Doenges · Nastätten, DE
• Thomas Herwig · Eltville am Rhein, DE

Key dates

• Filing date: Jun 9, 1980
• Grant date: Dec 22, 1981
• Expiry date: Jun 9, 2000

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S250/01
• WIPO field: Control
• WIPO sector: Instruments

Abstract

In an infrared motion alarm an optical filter arranged in front of an input of an infrared detector is attached to a heat sink in the form of a solid metal crucible in order to reduce the sensitivity to glass-penetrating electromagnetic radiation. Changes in radiation absorbed in the optical filter are either captured in the thermal sink or decelerated at least as to the characteristic thermal radiation of the optical filter and no longer fall within the characteristic range of change of the motion alarm.