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:
May. 21, 1996
Filed:
Aug. 11, 1993
Jeffrey K Fergason, Menlo Park, CA (US);
Other;
Abstract
A welding helmet including an optical protective lens including one or more liquid crystal cells as a variable optical transmission device responsive to a prescribed input to vary light transmission and light blocking characteristics thereof, and a hot mirror band pass filter having a relatively wide transmission characteristic in the visible spectrum and filtering characteristics in the infrared spectrum, the variable optical transmission device being tuned to provide a warning to indicate a nonoperating condition; and the variable optical transmission device being operative in a drive to dark mode for fast operation. Also disclosed is a method for protecting the eyes of a welder while providing a bright clear state, a fast switching to dark state, and the providing of an indication of a power off or failure state.