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John D Fergason, Jeffrey K Fergason, Arthur L Berman, James L Fergason: Eye protection device for welding helmets. OSD Envizion Company, Renner Otto Boisselle & Sklar, May 4, 1993: US05208688 (132 worldwide citation)

Light transmission control device includes band pass filter for transmitting light of a wavelength or group of wavelengths and partially blocking transmission of light of a different wavelength or group of wavelengths, and variable optical filter for controllably transmitting light of a wavelength o ...


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Jeffrey K Fergason, Arthur L Berman, James L Fergason, John D Fergason: Eye protection device for welding helmets which reduces obliquely incident light. OSD Envizion Company, Renner Otto Boisselle & Sklar, May 7, 1996: US05515186 (52 worldwide citation)

A welding helmet and lens therefor includes a shield and a lens including a two identical optical components, each including a polarizer, a further polarizer (analyzer) optically between said optical components and effectively shared as an output device from one optical component and an input device ...


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Jeffrey K Fergason, John D Fergason: Electro-optic light shutter and frame assembly with integrated switching mechanism. OSD Envizion Company, Renner Otto Boisselle & Sklar, December 27, 1994: US05377032 (49 worldwide citation)

A frame assembly for a light shutter including a frame structure for enclosing an electro-optic shutter assembly, the frame structure having a front surface which can be positioned opposite a cover lens, and a switch for controlling an operation mode of the electro-optic shutter assembly, the switch ...


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John D Fergason: Detector system for detecting the occurrence of welding. OSD Envizion Company, Renner Otto Boisselle & Sklar, September 28, 1993: US05248880 (39 worldwide citation)

A sensor circuit for detecting light hazards or bright light sources that will cause discomfort. The sensor and sensor electronics which provide a wide sensitivity range which is fully automatically adjustable, and which has the ability to detect point sources of light. The sensor further has the ab ...


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John D Fergason, Jeffrey K Fergason: Detector system for detecting the occurrence of welding using detector feedback. OSD Envizion Company, Renner Otto Boisselle & Sklar, October 12, 1993: US05252817 (34 worldwide citation)

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 stat ...


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John D Fergason: High speed, low power driving circuit for liquid crystal shutter. OSD Envizion Company, Renner Otto Boisselle & Sklar, September 13, 1994: US05347383 (21 worldwide citation)

A driving circuit for a liquid crystal shutter or for other devices that reduces the power drain on the portable power supply and has the characteristic of fast response time. Accurate voltage regulation also is provided by referencing an accurate reference voltage supplied by a diode.


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Fergason John D, Fergason Jeffrey K, Berman Arthur L, Fergason James L: Eye protection device for welding helmets and the like. Osd Envizion Company, Fergason John D, Fergason Jeffrey K, Berman Arthur L, Fergason James L, SKLAR Warren A, August 20, 1992: WO/1992/014183

A welding helmet includes a shield (2) and a lens (5) which has both a rapid driven to dark state during which eye (10) protection is provided during welding, a clear state during which maximum clarity is provided for viewing through the lens (5) when welding is not occurring, and a fail state that ...


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Fergason John D, Fergason Jeffrey K: Liquid crystal lens driver electronics for eye protection and high speed shuttering. Osd Envizion Company, SKLAR Warren A, October 1, 1992: WO/1992/016820

A power supply circuit (14) for a liquid crystal welding lens (10) or shutter develops a relatively low voltage AC signal for driving or powering the liquid crystal shutter (10) to the clear state and two relatively higher or larger magnitude AC electrical signals for initially driving the shutter ( ...