| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared crime-prevention sensor, when a detection signal level (light-receiving sensitivity) is adjusted by a projection power control, capable of preventing an erroneous detection by accurately detecting an occurrence of optical axis fluctuation after finishing the adjustment of an optical axis.SOLUTION: When projection power control means 5 adjusts a detection signal level (light-receiving sensitivity), optical axis fluctuation detecting means 36 detects an occurrence of optical axis fluctuation on the basis of a comparison between a light-receiving sensitivity level, obtained before installing a cover, when finishing the optical axis adjustment by a projection power control in an optical axis adjustment state, with a light-receiving sensitivity level, obtained after the installation of the cover, after the projection power has been adjusted according to a decrease in a transmittance of the cover; and displays the occurrence of the optical axis fluctuation with a display D. |
