Sensitivity control manner and sensitivity control device null of photoelectricity type smoke

摘要

PURPOSE:To facilitate the setting of sensitivity and adjusting operation and moreover, enable the adjusting of a smoke sensor without variations with a simple construction by arranging an adjusting piece outside a projection area of a projection element in a smoke detecting section to be displaceable within a photo detecting area of a photo detector. CONSTITUTION:When a smoke sensor is put into operation, light from a projection element 6 is projected to a projection area L1 in a smoke detecting section D. On the other hand, an adjusting piece 94 is outside a projection area L1 of the projection element 6 and reflected lights of one order or several orders of a direct light of the projection element 6 are incident into a reflecting surface 98. Here, when a screw shaft 95 of a cover for adjustment is loosened and the adjusting piece 94 is started to turn centered on the screw shaft 95, the reflecting surface 98 begins to approach the projection area L1 of light projected from the projection element 6. As a result, reflected light incident into the reflecting surface 98 increases and with the increase in the reflected light, scattered light increases irradiating a detector 7 through a photo detecting area L2. This causes a change in quantity of light received by the photo detector 7 to allow the adjusting of detection sensitivity of the photo detector 7, thereby enabling the adjusting of sensitivity of the smoke sensor.