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:
Dec. 06, 2011
Filed:
Jul. 25, 2008
Seiichi Hashimoto, Hamamatsu, JP;
Junichi Fujimori, Hamamatsu, JP;
Seiichi Hashimoto, Hamamatsu, JP;
Junichi Fujimori, Hamamatsu, JP;
Yamaha Corporation, , JP;
Abstract
A speaker capable of properly adjusting a spring characteristic with which a voice coil is driven and capable of being driven in large amplitude. When a position control coil wound around a bobbin is at a reference position, both ends of the coil cross a magnetic gap formed between external and internal yokes by a predetermined length and Lorentz forces acting on the front and rear ends are balanced. When the voice coil moves in either forward or rearward direction, lengths of the magnetic gap crossed by the front and rear ends of the control coil are different therebetween, and the vector sum of Lorentz forces acting on the position control coil is opposite in direction from the movement of the voice coil, whereby the voice coil is stably held at the reference position.