Light shield for welder's mask
First Claim
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1. A welder'"'"'s eyeshield comprising:
- a headpiece provided with a window subdivided into a passive first section of constant light attenuation and a voltage-controlled second section of variable light transmissivity juxtaposed with said first section;
photoelectric sensing means on said headpiece generating an output signal in response to incident radiation potentially damaging to the user'"'"'s eyesight; and
circuit means connecting said sensing means to said second section for maintaining same more highly transparent to visible rays than said first section in the absence of said output signal and for significantly reducing the light transmissivity of said second section in the presence of said output signal.
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Abstract
A welder'"'"'s helmet has a window with an upper section of invariable light-attenuation characteristics and a dimmable lower section comprising an ultraviolet filter, an infrared filter, and an electro-optical shutter such as a liquid crystal sandwiched between a polarizer and an analyzer. A control circuit including a UV-sensitive photocell, upon sensing a welding arc or flame, operates the shutter to reduce the amount of light transmitted through the lower section of the window.
88 Citations
9 Claims
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1. A welder'"'"'s eyeshield comprising:
- a headpiece provided with a window subdivided into a passive first section of constant light attenuation and a voltage-controlled second section of variable light transmissivity juxtaposed with said first section;
photoelectric sensing means on said headpiece generating an output signal in response to incident radiation potentially damaging to the user'"'"'s eyesight; and circuit means connecting said sensing means to said second section for maintaining same more highly transparent to visible rays than said first section in the absence of said output signal and for significantly reducing the light transmissivity of said second section in the presence of said output signal. - View Dependent Claims (2, 3, 4, 5, 8, 9)
- a headpiece provided with a window subdivided into a passive first section of constant light attenuation and a voltage-controlled second section of variable light transmissivity juxtaposed with said first section;
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6. A welder'"'"'s eyeshield as defined in claim 6 wherein said first section comprises an ultraviolet filter and an infrared filter.
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7. A welder'"'"'s eyeshield as defined in claim 7 wherein the optical density of said first section substantially equals that of said second section in the de-energized state of said liquid crystal.
Specification