The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 16, 2010
Filed:
Mar. 04, 2008
Kenichi Kato, Tokyo, JP;
Kenichi Kato, Tokyo, JP;
Nohmi Bosai Ltd., Tokyo, JP;
Abstract
A smoke detector having a structure in which, at a time of performing smoke detection, an S/N ratio of a signal of a light receiving element is improved, to thereby accurately detect the occurrence of a fire. At opposite end portions of an inside of an optical case () having a substantially cylindrical shape, a light emitting element () and a stray light portion () are arranged. In the stray light portion (), a light trap () is provided. Further, in the vicinity of the light emitting element (), a condenser lens () is provided to allow light L to be incident on a curved surface of the light trap (). At the time of smoke detection, light scattered by smoke particles in a smoke detection portion () is received by a light receiving element (). However, the light that is incident on the light trap () is reflected on the curved surface a plurality of times to be attenuated in each reflection, so the light is not received by the light receiving element (). Accordingly, the S/N ratio of an output signal S obtained from the light receiving element () is improved, thereby making it possible to accurately perform smoke detection at an early stage.