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:
Apr. 29, 2003
Filed:
Feb. 05, 2001
Kazuhiro Akiho, Saitama, JP;
Masaki Kusuhara, Saitama, JP;
Hiroyuki Watanabe, Saitama, JP;
Tomoyasu Uno, Saitama, JP;
Nanwa Quartz, Inc., Tokyo, JP;
Abstract
Present invention suppresses undesirable effects of the bubbles trapped in a silica glass crucible on single crystallization during the pulling process under a high-temperature load. When raw material powder is melted in a mold graphite components of electrodes and impurities contained in the raw material are removed by introducing hydrogen gas and/or oxygen gas immediately after the start of arc discharge. Graphite and impurities are prevented from entering the product crucible, thereby suppressing the volume increase rate of the bubbles and reducing the inner pressure of the bubbles. Gases remaining in voids of an accumulated layer of silica powder formed inside the mold can be replaced with helium gas, by supplying helium gas to the accumulated layer from the mold