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:
Nov. 01, 2011
Filed:
Jul. 25, 2008
Takeshi Fujita, Akita, JP;
Minoru Kanda, Akita, JP;
Takeshi Fujita, Akita, JP;
Minoru Kanda, Akita, JP;
Japan Super Quartz Corporation, Akita-Shi, JP;
Abstract
The method of producing a vitreous silica crucible, comprises deposition step of depositing silica powder on an inner wall surface of a cylindrical rotation mold having a bottom while rotating the mold; and a fusion step to obtain a vitreous silica crucible by heating and fusing the silica powder deposited on the inner wall surface of the mold and thereby vitrifying the silica powder. In the deposition step, a density of the deposited silica powder layer on the inner wall surface of the mold is controlled within a predetermined range by controlling the electrostatic charging voltage of the silica powder to be in a range of 1.0 kV or less in absolute value, and supplying the thus controlled silica powder to the inner wall surface of the mold. Thus, a wall thickness of the vitreous silica crucible is controlled.