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. 28, 1995
Filed:
Sep. 30, 1993
Jorg Prokisch, Schwarzach, DE;
Nokia Technology GmbH, Pforzheim, DE;
Abstract
It is known in the state of the art to equip conical loudspeakers, which are suitable for reproducing long excursion or wide band audio signals, with magnet systems (10), which contain a ring-shaped permanent magnet (12) made of ferrite. To make the induction, required by these magnet systems (10), available in the air gap (20), it is necessary to design the permanent magnets (12) in a large size. It is also known to construct short excursion magnet systems in such a way, that the pole core is made of a high energy magnetic material (-neodymium). This pole core is located in the center of a pot magnet. Such magnet systems, which have the same output and can be built considerably smaller and lighter than the types of magnet systems (10) mentioned first, cannot be transferred to the magnet systems (10) that are suitable for the reproduction of wide band or long excursion audio signals, because a neodymium pole core is not able to produce the induction in the air gap required by such magnet systems (10). The invention therefore equips a conventional magnet system (10) with a pole core (13), which is at least partly made of neodymium. This measure makes it possible to lighten the magnet system by at least 50%, as compared to conventional magnet systems (10), with the same induction in the air gap (20) and the same air gap dimensions.