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Anti-Dazzle Windshields again

polarize windscreen and main beam for better night vision
  (+2, -1)
(+2, -1)
  [vote for,

Place a polarizing layer, aligned at 45 degrees, in the windscreen and, at the same angle, also over the main lights. Then light from cars facing toward you will be at 90 degrees to the polarizer in your windscreen and so be much reduced in intensity, but your lights reflections will be slightly enhanced, relative to other sources of light, by having a higher percentage aligned with your windscreen. Maybe this will reduce the need for a dip beam and the action of having to trigger it.
psiplace, May 07 2005

RonD, anonymous halfbaker http://www.halfbakery.com/user/RonD
He's posted no ideas, but he does delve into the history of this concept at length. [waugsqueke, May 07 2005]

Halfbakery search: "polarized headlights" http://www.halfbake...olarized+headlights
Many mentions. [waugsqueke, May 07 2005]


       Does this exist for rear glass? I seem to have slid to below the line of average vehicle height, consequently at eye level to the beams from taller vehicles.
reensure, May 07 2005

       well it could, by having the polarizer going at right angles to the front one, but this would mean you couldn't see right through a car, which is quite useful for following cars. BTW do you realise this is an idea, and doesn't actually exist?   

       but the 4x4 thing is quite interesting, large car dipped beams don't help low cars close up, i know this after having been rendered unable to drive by one on a narrow back road a few month ago, after it flashed me thanks for letting it through.
psiplace, May 07 2005

       You might have an issue during the daytime if you wear polarized sunglasses while driving. (I do, it cuts down on glare and reflections in the windshield). The 45 degree polarizer won't be aligned with the solar polarizer, and it will make the window seem darker.
krelnik, May 07 2005

       yes, kind of thought about that, the real problem with polarized sunglasses would be that if you tilted your head to 45 degrees, the screen could go completely black!! so i think they would have to be a no-no. A little bit more expensive solution would be an active polarizer in the screen, as in the liquid crystals of an LCD.
psiplace, May 07 2005

       Nothing new here. This is a very old concept. A bakery search alone pulls several annotation references, and indications this has been posted a couple of times already.
waugsqueke, May 07 2005

       the Halfbakery: "polarized headlights" idea was so rediculous i wasn't sure it was a joke, but it prompted this entry hence "again", the "Description of Suspended Particle Device" is about darkening glass, this entry isn't. i deleted it. the "RonD, anonymous halfbaker" is about the same thing and is very good but i think it is wrong about the problems with lowered intensity, contract is more important, you can half the amount of light but if you improve its contract, you make for clearer vision.
psiplace, May 07 2005

       [psiplace] may not be the first to have thought of this, but I think it is such a neat idea.   

       In his profile RonD mentions that new brighter polarized headlights might be a problem for drivers of older cars. I don't think so: polarized sunglasses with the appropriate 45 degree slant would be widely available for around $10. These sunglasses can be a good substitute for the polarized windshield.   

       There would also be aftermarket retrofit kits for headlights.   

       This is such a good idea it should really be done. I can see this saving many more lives then the mandatory airbags, at a fraction of the cost.
jmvw, Sep 12 2006

       //I can see this saving many more lives then the mandatory airbags, at a fraction of the cost//   

       Don't worry, they'll figure out a way to make it cost more.   

       "I'm sorry sir, but it looks like your car is totalled."   

       "What? It's just a cracked headlight!"   

       "Yes sir... totalled. It would cost more to buy a new car than to replace the headlight."
ye_river_xiv, Sep 12 2006

       I was thinking about this concept on on googling it, discovered that the founder of Polaroid came up with this in the 1920s. The auto industry never implemented it. These are the same folks who had to be forced to install seatbelts in their cars.
bungston, Jun 05 2007

       Following on from a previous anno - Seatbelts don't work either: if you angle your head just so, and move your arms and legs just so, then when you have an accident, lo and behold, an injury is sustained.   

       Why the polarised headlight idea is not implemented, in some form or other, is something that I cannot completely understand.
I guess it might equate to some kind of safer than safe thinking. Another example is using the ABS sensors to signal a flat tyre (rotation speed differential), but I read that there 'might be a false sense of security' with such a system on a few web-sites.
Or it might be that there is a patent on the idea, and the license is unacceptable.
Ling, Jun 05 2007

       There's an article in a recent Scientific American issue about this. They think it's simply corporate inertia that's prevented its universal adoption.
Cosh i Pi, Jun 05 2007


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