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:
Apr. 01, 2003
Filed:
Jun. 03, 2002
Applicant:
Inventors:
Thomas Hänisch, Berlin, DE;
Peter Frank, London, GB;
Assignee:
MSA Auer GmbH, Berlin, DE;
Primary Examiner:
Int. Cl.
CPC ...
H04R 1/700 ; H01L 4/109 ;
U.S. Cl.
CPC ...
H04R 1/700 ; H01L 4/109 ;
Abstract
In a piezoelectric acoustic alarm piezoelements ( ) each excited by a square-wave voltage are arranged opposite each other in a resonance cavity ( ) and each oscillate in opposing directions. The two square-wave voltages (V , V ) controlled by a microprocessor ( ) are phase displaced by a square-wave pulse length and are positive or negative. A piezo-sound source designed and excited in this way is characterised by a high sound volume with low current consumption and small size.