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:
Jun. 09, 1998
Filed:
Jul. 11, 1995
Tooru Ikeda, Vancouver, WA (US);
Kazuo Asajima, Nanjo-gun, JP;
Hiroshi Kimura, Fukui, JP;
Hiroyuki Watanabe, Takefu, JP;
Shin-Etsu Quartz Products, Ltd., Tokyo, JP;
Heraeus Quarzglas GmbH, Hanau, DE;
Abstract
In a quartz glass crucible obtained by heating and fusing a rotating layer (3) charged with a powder of silicon dioxide, impurity elements are controlled so that copper, chromium, and nickel each amount to 0.5 ppb or less, iron amounts to 120 ppb or less, and sodium amounts to 20 ppb or less. The silicon dioxide powder is supplied to a rotatable mold (1) having an open top, thereby forming a layer (3) charged with silicon dioxide along the inner peripheral wall of the mold. The layer (3) is internally heated and fused while covering the open top with a lid (5) having two or more holes (6,7), and the mold (1) is ventilated to discharge the high temperature gases through the holes (6,7).