Eye protection device for welding helmets
US5208688A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 8, 1991 |
| Grant date | May 4, 1993 |
| Priority date | — |
| Expiry date | Feb 8, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2203/05
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
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 or group of wavelengths, the band pass filter and variable optical filter being cooperative to provide at least three light transmitting modes, including maximum transmission, minimum transmission, and a third mode less transmissive than the maximum, the device being operative to minimum transmissive mode upon being driven by a maximum energy input, the device also being operative to maximum transmissive mode upon being driven by a lesser energy input, and such third transmission mode occurring in response to no power or a failure of power or adequate power for energizing the device to the maximum or minimum transmissive mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.