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:
Aug. 08, 1989
Filed:
Feb. 19, 1988
Mitsuru Yoshida, Fujioka, JP;
Mitsubishi Pencil Co., Ltd., Tokyo, JP;
Abstract
A process for producing a diaphragm for a speaker of carbonaceous materials which includes the steps of mixing carbon powder in a binder mainly containing chlorine-containing vinyl resin to be carbonized after calcining, applying high shearing force to a mixture composition obtained by uniformly mixing and dispersing the resultant mixture to sufficiently knead the mixture, then preliminarily molding the resultant mixture in a sheet shape, molding the preliminarily molded sheet into a diaphragm, insolubilizing, infusibilizing the diaphragm and calcining the diaphragm in an inert atmosphere, wherein the mixture composition contains at least 0.1 to 5 percentage by weight of 1.8-diazobicyclo (5, 4, 0) undecene-7 or that in which its salt is chlorine-containing vinyl chloride. Thus, the process can simply and inexpensively produce a diaphragm having a high hardness, a high elasticity, a high strength, a light weight, an adequate internal loss, and thus less deformation by an external force, small distortion of sound, wide reproducing sound range, distinct sound quality and suitable for digital audio applications.