TRANSMISSIVITY MEASURING DEVICE

• Main Author: FUKUDA NORISUKE
• Format: Patent
• Language: English
• Published: 17.02.1988
• 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 detect smoke with high sensitivity, by a method wherein a reflecting surface is provided to a light receiving chamber and light is separated into the longest measuring light path and the shortest reference light path and the light receiving output from the reference light path is controlled so as to become constant to perform the correction control of the light from a light source. CONSTITUTION:Air containing smoke is introduced into a light receiving chamber 3 and reflecting surfaces 8a-8g being optical mirror surfaces are formed to the inner wall of the light receiving chamber 3. The light from a light source 9 is separated into a measuring light path and a reference light path by a half mirror 10. The measuring light path is formed as the longest light path consisting of star-shaped light paths 13a, 13b, 13c, 13d...13h by the reflecting surfaces and measuring light is received by a first light receiver 11. Further, the reference light path is formed as the shortest light path consisting of light paths 14a-14h and light is received by a second light receiver 12. Then, the light receiving output of the second light receiver 12 is controlled by a correction means so as to always become constant. Since, the light receiving output of the second light receiver 12 is controlled so as to become constant and the intensity of the light from the light source is corrected, the variation in the extinction quantity of measuring light due to the contamination of the reflecting surface is prevented and a smoke sensor can be constituted with high accuracy.