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. 20, 2000
Filed:
Apr. 10, 1997
John R Easoz, McMurray, PA (US);
Takashi Isobe, Bethel Park, PA (US);
Ebara Solar, Inc., Large, PA (US);
Abstract
The amount of silicon feed material supplied to a silicon melt furnace in a silicon crystal web growing installation is controlled by providing a melt level reference signal, generating a melt level signal representative of the level of the molten silicon in the silicon melt furnace, and providing a feed rate control signal representative of the difference between the melt level signal and the melt level reference signal. The feed rate control signal is used in a open loop mode to advise an operator of the amount of adjustment needed to correct the melt level; and is used in a closed loop mode to control the feed rate of the silicon feed material to the furnace. The laser beam reflected off the melt surface is passed through a narrow bandpass filter to remove noise due to thermal radiation from the furnace. The melt level signals generated by a position detector are averaged and digitally filtered to eliminate erroneous data caused by mechanical vibrations and other noise sources.