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Photochromic windshield

Coated with (polarized) photochromic layer.
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Windshields and windows that automatically react to the amount of light outside, such as the already-available sunglasses that do the same. Polarize the photochromic layer so as to make it react quicker to directional light that the driver would see. i.e. driving down the road, some idiot has brights on, photochromic layer darkens only in area where driver would see the spots of the light. Alternately, low-cost LCD technology might allow entire windows to be darkened to a user-selected setting...and high-cost LCD technology might allow a full-screen [windshield] night vision overlay, maybe even before I die of old age! Sorry if this is a re-bake, I searched, I swear.
DrOuD, Mar 19 2003

Photochromic Ink Link http://www.ctiinks.com/products/photo/
Someone offering photochromic inks that might easily be added to the plastic film inside your windshield...these only react to UV, though, which would be perfect for the original idea. [DrOuD, Oct 17 2004]

[link]






       Unfortunately, the photochromic layer would have to be applied to the *outer* surface of the windshield, since applying it on the inside would seriously inhibit its ability to darken, due to the filtering of UV light through the glass. The layer would then be subject to abrasion and wear, mostly from the windshield wipers.
Cedar Park, Mar 19 2003
  

       Good point. Aren't special additives required (and added) for glass to [efficiently] block UV? Also, the photochromic effect isn't unique to UV...normal white light can set off several types of photochromic substances.
DrOuD, Mar 19 2003
  

       What's the reaction time of modern photochomic materials? I'd hate to go from bright sunlight into a tunnel only to find myself blinded by my windscreen.   

       (Oh, and if you want to darken the windscreen only with respect to the driver, you need some kind of lensing effect or collimator infront of the windscreen.)
st3f, Mar 19 2003
  

       Reaction time of most photochromic materials is in minutes...alternately, technology such as is employed in welding visors may be better suited, as it reacts *very* quickly. However, windshields cannot have very dark tint by law in any case...the idea would be an eye-strain reducer, not full 80% tinting or some such. The small amount of tint would not affect tunnel driving...if a tunnel is not lit, the transition blinds the typical driver in any case.   

       Yes, you would need to polarize and align the photochromatic molecules to react only to light focused on the [average] driver's viewing angles. A photochromic molecule with an iron component would make this easy...align them with a magnet before drying or fixing in place.
DrOuD, Mar 19 2003
  

       Useless comment, UnaBubba? Explain.
DrOuD, Mar 19 2003
  

       [UnaBubba] is indicating that he has voted against the idea (fishboned it). A positive vote is indicated by a Croissant. The HELP file in the "meta" section explains voting.   

       Welcome to the HalfBakery.   

       I like the idea of using the welding-shield fast reacting system.
8th of 7, Mar 19 2003
  

       Fisheye lenses ?
8th of 7, Mar 19 2003
  
      
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