| 摘要 |
716,654. Photo-electric smoke detectors. KIDDE CO., Ltd., W. July 1, 1953 [April 28, 1952], No. 10626/52. Class 40 (3) In a photo-electric smoke detector smoke enters a casing through an inlet 2 and leaves through an outlet 4 and a beam of light produced by a source 5 and lens 6 illuminates the smoke. Photo-cells 7 mounted on a pentagonal frame receive light diffused from the smoke, these cells forming one arm of a Wheatstone bridge circuit a balancing arm being constituted by a further cell 8 arranged with its face immediately above and facing the light beam. A vertical mask 9 blocks nearly the entire width of the light beam and enables cell 8 to receive only a narrow beam of light the intensity of which is reduced due to the presence of smoke rather than increased. A vertical mask may be provided in front of the photo-cell and the cell may be vertically adjustable. Specification 625,731 is referred to. |
