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:
Aug. 27, 2013
Filed:
Oct. 21, 2008
Yoshifumi Watabe, Tondabayashi, JP;
Yoshiaki Honda, Souraku-gun, JP;
Masanori Hayashi, Kadoma, JP;
Yuji Takada, Kyoto, JP;
Takayuki Nishikawa, Osaka, JP;
Yoshifumi Watabe, Tondabayashi, JP;
Yoshiaki Honda, Souraku-gun, JP;
Masanori Hayashi, Kadoma, JP;
Yuji Takada, Kyoto, JP;
Takayuki Nishikawa, Osaka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
A fire alarm system, determining existence or nonexistence of a fire by using an ultrasound wave, comprises a sound wave generator and a sound wave detector to detect sound waves propagated through two propagation paths having different lengths each other. The system comprises a calculation means for calculating a pressure ratio between a first sound pressure, which is a sound pressure of a sound wave propagated through a first propagation path, and a second sound pressure, which is a sound pressure of a sound wave propagated through a second propagation path, and a smoke density estimator. The smoke density estimator calculates a change ratio between the pressure ratio calculated by the calculation means and a predetermined standard pressure ratio, and determines a smoke density from the change ratio based on a predetermined relational expression describing the relation between the change ratio and the smoke density, and determines existence of a fire when the smoke density exceeds a predetermined threshold.