Heat-ray sensor

Abstract

An object of the present invention is to provide a passive infrared detector which can surely discriminate an intruder and a small animal passing proximately to the detector without detracting the performance for detecting the intruder within the guard coverage area (alert object area). According to the present invention, there is provided a passive infrared detector for detecting a moving objectsuch as intruder comprising an optical unit having a PCB (print circuit board) disposed in front of a base and mounted thereon a plurality of lenses vertically arranged at predetermined spaces and detecting elements arranged at positions corresponding to the lenses, and a control means for processing signals detected by the detecting elements characterized in that the spaces between the pluralityof lenses are set so that they are small for a size of a human body and large for a size of a small animal, and that the control means are adapted to judge whether the moving object is an intruder ora small animal by discriminating the simultaneity of signals detected by the detecting elements or by summing the detected signals.

Description

technical field [0001] The present invention relates to a passive infrared detector for detecting an intruder as a moving object by detecting thermal changes of far-infrared radiation from a human body by using a pyroelectric element. Background technique [0002] Typically, a passive infrared detector includes a housing or container formed from a plurality of mirrors and an optical unit mounted on the tip of a pair of side walls extending from the end of the housing and including a PCB (Printed Circuit Board) of pyroelectric element, this passive infrared detector is suitable for detecting intruders (i.e. human body) within the guard coverage area (alarm object area) by detecting thermal changes of far-infrared radiation using the pyroelectric element . [0003] In this passive infrared detector, there is provided a method of forming a single system in one optical unit by using a plurality of elements arranged with a plurality of pyroelectric elements, or by utilizing a pa...

AI Technical Summary

Problems solved by technology

[0004] However, prior art passive infrared detectors are effective in preventing false information from being generated at locations where a person who is the subject of detection walks (typically at a location about 2m-30m away from the passive infrared detector)

Therefore, it is difficult to maintain a sufficient warning zone and is thus ineffective in preventing the generation of false information related to small animals moving close to the passive infrared detector

Although a passive infrared detector utilizing multiple optical elements with wide spacing between them has been proposed, it is difficult to maintain a sufficient distance for small animals because the purpose of providing wide spacing is different from preventing the generation of false information. Distinguishing between human body (human) and insects or birds flying near the detector or crawling onto the surface of the detector

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