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:
Mar. 10, 1987
Filed:
Nov. 05, 1984
Adrianus J Kaizer, Eindhoven, NL;
Frederik L Sangster, Eindhoven, NL;
Cornelis A Wesche, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A device for converting an electric signal into an acoustic signal, which comprises an electro-acoustic transducer unit (2) having a quality factor (Q) less than unity. The device further comprises an amplifier circuit (3) for driving the transducer unit. The amplifier circuit has a frequency-dependent gain characteristic (6) which increases towards the lower frequencies, starting from f.sub.2, in a frequency range between a first and a second frequency (f.sub.1 and f.sub.2), f.sub.1 being the resonant frequency of the transducer unit (2) and f.sub.2 being greater than f.sub.1. The efficiency can be increased if amplifier the circuit includes a special amplifier such as a switched amplifier, for example, a class-D amplifier, or an amplifier with a power supply that provides a DC voltage that depends on the drive level of the amplifier.