Infrared intrusion detector

US4709152A · kind A · utility

Assignee

• Cerberus AG · CH

Inventors

• Kurt Muller · Zürich, CH
• Peter Gruber · Renningen, DE
• Alfred Wuthrich · Bern, CH

Key dates

• Filing date: Jan 13, 1986
• Grant date: Nov 24, 1987
• Expiry date: Jan 13, 2006

Classification

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

Abstract

An infrared intrusion detector having a predetermined number of rows of radiation reception zones comprises a primary reflector and a secondary reflector for each row of radiation reception zones. The primary reflectors and their associated secondary reflectors form a folded radiation path. The folded radiation path allows for compact construction and simple manufacturing of the infrared intrusion detector. One reflector of each radiation reception zone forms together with the infrared sensor a compact structural unit. The other reflectors of each radiation reception zone are combined to form a further structural unit which is arranged in a predetermined spaced relationship to the first compact structural unit. In order to achieve uniform detection sensitivity in radiation reception zones having different angles of inclination to the horizontal plane, a larger focal length is chosen for radiation reception zones with smaller angles of inclination and longer range. Likewise, to achieve uniform detection sensitivity even with oblique infrared radiation impingement, the surface area of the primary reflectors increases within each horizontal row from the middle to the sides.