| 摘要 |
<p>PURPOSE:To surely detect the existence of an object even in the case of an object whose moving speed is high by providing a pair of pyroelectric elements arranged on almost the same surface, and a slit plate on which a slit train is formed in two lines corresponding to each pyroelectric element. CONSTITUTION:Between both pyroelectric elements 1a, 1b, a light shielding plate 6 is provided so as to be orthogonal to the array surface of both the pyroelectric elements 1a, 1b. Also, this light shielding plate 6 is provided so that heat rays passing through each slit train is made incident independently on each pyroelectric element 1a, 1b, respectively. In this case, by slits 5a constituting each slit train, plural detection areas A are formed, and although the constitution is simple, plural detection areas A can be allowed to correspond to one pyroelectric element 1a, 1b. Also, the sensitivity to the heat rays which are made incident from the direction inclined by an angle theta to the normal direction of a pyroelectric sensor 2 becomes cos theta folds of that of the front direction, therefore, there is no extreme variance of sensitivity caused by the incident direction of the heat rays.</p> |
