METHOD AND APPARATUS FOR ADJUSTING SENSITIVITY OF PHOTOELECTRIC TYPE SMOKE SENSOR

• Main Author: HORIUCHI SATOSHI
• Format: Patent
• Language: English
• Published: 27.03.1991
• Subjects: ALARM SYSTEMS; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; ORDER TELEGRAPHS; PHYSICS; SIGNALLING; SIGNALLING OR CALLING SYSTEMS; TESTING

PURPOSE:To facilitate the setting of sensitivity and adjusting operation while enabling adjustment of sensitivity of a smoke sensor accurately by arranging an auxiliary light emitting element with a variable quantity of light outside a projection area of a projecting element and a light receiving area of a photo detector in a smoke detecting section. CONSTITUTION:A cover 82 of a body 1 of a smoke sensor 1 taken out is removed and a cover 5 is taken off to be replaced with an adjusting cover 9. Then, when the smoke sensor 1 is put into operation, a projection light of a projection element 6 is projected to a light receiving area L2 within a smoke detecting section D and a projection light of an auxiliary light emitting element 94 lighted synchronously though an auxiliary light emitting circuit and these scattered lights are incident into a light receiving element 7. Here, when current flowing through the element 94 is increased little by little by operation of the auxiliary light emitting circuit of the smoke detecting section D, quantity of light projected of the auxiliary light emitting element 94 is increased. With an increase in the element 94, the scattered lights irradiating the light receiving element 7 through the light receiving area L2 is also increased. As a quantity of light incident into the light receiving element 7 increases to reach a fixed value, the smoke sensor 1 shifts to operation state from non-operation state. Thus, unadjusted sensitivity is adjusted from the level of current at the moment.