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:
Jun. 03, 2003
Filed:
Apr. 24, 2000
Shoji Tanaka, Hyogo, JP;
Matsushita Electric Industrial Co., Ltd., Kadoma, JP;
Abstract
Negative stiffness is generated for a vibration system of a speaker unit by using a movable magnet attached to the vibration system of the speaker unit and also a ring-like stationary magnet arranged coaxially at the outer radius thereof in order to increase equivalently internal volume of a cabinet. In addition, an offset in the displacement direction of the vibration system of the speaker unit is detected with a Hall element and fed back to a power amplifier in order to correct the offset in the displacement direction of the vibration system of the speaker unit. As a result, a reliable and practical bass reproduction speaker apparatus can be obtained, and the speaker apparatus is noise-free and excellent in bass reproduction performance even with a cabinet of small capacity.