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:
Oct. 12, 1993
Filed:
Mar. 25, 1991
Applicant:
Inventors:
John D Fergason, Sunnyvale, CA (US);
Jeffrey K Fergason, Menlo Park, CA (US);
Assignee:
OSD Envizion Company, Menlo Park, CA (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01J / ;
U.S. Cl.
CPC ...
250205 ; 2502 / ; 2502 / ;
Abstract
A power supply circuit for a liquid crystal welding lens or shutter develops a relatively low voltage AC signal for driving or powering the liquid crystal shutter to the clear state and two relatively higher or larger magnitude AC electrical signals for initially driving the shutter to the dark state and then for maintaining the shutter in the dark state; a variable frequency circuit for varying the frequency of the driving signal to the shutter to minimize power usage in the dark state and to avoid flicker in the clear state; and power saving and battery level indicator features are included.