PURPOSE: To make it possible to ensure the detection regardless of the concentration of smoke, by detecting the difference between the received light signal when smoke enters a flowing space and a reference signal.
CONSTITUTION: A light emitting element 13 is arranged so as to face a reflecting surface 11f of a light reflecting body through a flowing space A of smoke. Light is emitted toward the space A. A light receiving element 14 is separately arranged so as not to receive the light of the element 13 directly. When the light from the element 13 is reflected by the reflecting surface 11f and the smoke in the space A, the element 14 receives the reflected light and generates a received light signal based on the quantity of the received light. A reference-signal generating means 15 generates a reference signal based on the received signal of the element 14 when the smoke is not present in the space A. When the smoke flows into the space A, a detecting means 20 detects the difference between the received light signal value of the element 14 and the reference signal value and generates the result as a detected signal.
YAMAMOTO TAKAAKI
ADACHI IZUMI
NAKAYAMA MASAO
KURAHASHI AKIRA
HAMAMATSU PHOTONICS KK
| JPS5580199A | 1980-06-17 | |||
| JPS5244783U | 1977-03-30 | |||
| JPS5742842A | 1982-03-10 | |||
| JPS5444582A | 1979-04-09 |