Infrared human detector not barred by an intervening obstruction

• US 5,489,892 A
• Filed: 12/06/1994
• Issued: 02/06/1996
• Est. Priority Date: 12/21/1993
• Status: Expired due to Term

• Current Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Original Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Inventors: Tomooka, Hiroyuki, Imuro, Yoshihiro
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US08/350,289
• Time in Patent Office: 427 Days
• Field of Search: 340/567, 250/DIG. 1, 250/338.1, 250/340
• US Class Current: 340/567
• CPC Class Codes: G08B 29/046 prevention of tampering with detection circuits
• CPC Class Codes: Y10S 250/01 Passive intrusion detectors

Abstract

An intruder detection system for senses infrared radiated by an intruder through a window-pane and detecting the intrusion through the reception of an output from the infrared sensors. The system includes a light emitter for projecting infrared rays toward a detection area and a light acceptor for receiving at least part of the infrared rays projected by the light emitter through an obstruction detection optical path. The light emitter and the light acceptor are located on opposite sides of the window-pane.

Claims

1. An intruder detection system for sensing infrared radiated by a human intruder through a window-pane and detecting the intrusion through the reception of an output from an infrared sensor, the system comprising a light emitter provided outside the window-pane so as to project infrared rays toward a detection area, a light acceptor provided inside the window-pane, the light emitter and the light acceptor being optically connected to each other by an obstruction detection optical path, the system further comprising a prism lens provided in front of the light emitter so as to produce an open optical path and a closed optical path.

2. An intruder detection system for sensing infrared radiated by a human intruder through a window-pane and detecting the intrusion through the reception of an output from an infrared sensor, the system comprising a light emitted provided inside the window-pane so as to project infrared rays toward a detection area, a light acceptor provided outside the window-pane, the light emitter and the light acceptor being optically connected to each other by an obstruction detection optical path.