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:
May. 12, 1998
Filed:
May. 26, 1995
Hiroshi Ueda, Hyogo, JP;
Kazuhiro Ohyama, Osaka, JP;
Shizuo Furuyama, Osaka, JP;
Kiyoshi Kojima, Nara, JP;
Masayuki Wakamiya, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A magnetic circuit unit for a loud-speaker is provided, in which an adhesion step can be reduced or omitted, magnetic properties can be improved through enhancement of magnetic efficiency, and a durable anti-corrosive treatment can be performed at low price, so that higher performance and lower cost of the loud-speaker can be attained. A method of manufacturing the same is also provided. A top plate has a conical, columnar, truncated conical, or partially spherical hollow part formed on one side whose inner surface is integrated with an anisotropic Nd--Fe--B system magnet under a forming pressure of 100 to 200 kgf/cm.sup.2 through Joule heating by passing a current under compression. The forming die is cooled to a temperature below 100.degree. C. while maintaining the pressure, and the compact is then taken out from the forming die. This integrated compact is adhered to an outer yoke, and a looped yoke and a loop anisotropic Nd--Fe--B system magnet are also adhered thereon to fabricate a magnetic circuit unit. Subsequently, this magnet circuit unit is dipped in acrylic resin emulsion, and a coating of 7 to 15 .mu.m thick is formed by using a rotary coating device.