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Discussion Starter #1 (Edited)
I have Polaroid sunglasses. :cool: When the asphalt is wet and you're driving towards the sun, you'll know why.

Well, I noticed that if I tilt my head slightly to the right, the Nav LCD screen turns completely black. With my head straight up, it's only at 50% brightness. Only by tilting my head left I see it at full brightness. The clock display behaves similarly, but at a slightly different angle. The phenomenon is caused by the fact the LCD screen's light is also polarized. If the polarization angle between your glasses and the screen is around 90 degrees, you see nothing.

This is not nearly as bad as it was with the Peugeot 1007 I test drove - the screen went completely black with when my head was upright.

Makes me wonder - do car LCD screen manufacturers even think about this issue? I thought people would be aware of this by now. Don't a lot of people wear polaroids when driving?

Is there any other way to fix this problem than replacing the LCD screen and hoping you get lucky? What determines the polarity of the screen anyway, is it the coating, or something in the pixels?
 

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i have a similar problem with my oakleys, so your not alone.
 

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Is there a chance that it's the sunglasses which are "random"?

I can't imagine that sunglass makers would bother which way around the polarization is, although I could be wrong.

Intrestingly (OK, maybe not) it's exactly what 3d cinema's use! One lens is polarized one way, one lens the other and then 2 projections, one polorized each way; so each eye sees a seperate image!
 

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Discussion Starter #5
Is there a chance that it's the sunglasses which are "random"? I can't imagine that sunglass makers would bother which way around the polarization is, although I could be wrong.
At least high quality sunglass manufacturers should bother about it, because the polarization direction has an effect on which reflections get filtered. The most important kind of reflection is sunlight shining off a horizontal surface (wet asphalt, ice, water), so the manufacturers orient the polarization accordingly.
 

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Discussion Starter #6
I checked Wikipedia. Apparently LCD screens have a polarizing filter sheet in them too. It's supposed to be vertical (just like sunglasses, so there should be no conflict), but apparently it's the LCD screen manufacturers that don't bother, because I've seen a lot of variety between LCD screens when looking at them through my glasses.

A standard should be estabilished. Any LCD screens intended for cars should be checked for vertical polarity. At least it doesn't seem like a common practice yet.
 

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I always have a pair of polarised sunnies in the car. I think the can quite literally be life saver.

All polarised glasses are orientated to cancel out refeltctions on the horizontal plane as Skaven pointed out. I have a polarising filter for my digital camera that has markings on it so you can orientate it which ever way you like.

I have found most LCD screens to have their polarisation at about a 45' angle.
 

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at £200 I'd like to think they were!
Ah the expensive goggles.

Back in the early 70's I wanted a decent pair of sunglasses so I went to an optician type shop. They sold me a pair of Zeiss Umbrals for £17.

Now bear in mind that at that time £17 was about a week and a half's wages ! Wonder what the equivalent is now ?

Oh - and I've still got them in the car and they are superb.
 

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Discussion Starter #12
I have found most LCD screens to have their polarisation at about a 45' angle.
Yeah, it seems rather arbitrary. As if, at the factory, they just cut out the pieces from the film at whichever orientation makes least material waste.

I think LCD screen manufacturers that make screens for cars should be informed of this problem. I just wish I knew how to inform them... :confused:
 

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Discussion Starter #13
at £200 I'd like to think they were!
If you want to test your sunglasses whether they are polarized or not, try tilting your head when looking at an LCD screen. If the screen's brightness changes, they're polarized.
 

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Adding polarisation to sunglasses is not especially expensive. But most oakleys aren't polarised IIRC. I have some oakleys that were RRP around that price, and they're definitely not polarised.
Most Oakleys are available polarized if you choose what lens you want, but most people will just buy the ones they think look good out of the display cabinet. A lot of the expensive Oakley glasses are just iridium lenes, but are available as polarized iridium if you want to pay more.
 

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I can't stand glare, my eyes start watering quite badly so I wear my sun glasses all year round - you may laugh but white cloud gives off a lot of glare, even in winter.

Oh and my glasses are polarised prescription sunglasses from Specsavers and they are brilliant. And I don't have any probs looking at displays. But I have noticed the same effect that Skaven252 notices in car parks that have lcd screens.
 

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I've got polarised prescription Oakleys (they took about a month to arrive and cost a small fortune but are awesome) and have no trouble with the displays in my car. You do notice a bit of ghosting on the lower section of the rear window with them though.
 

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mine say"polarised" on the left lense, they are the oakley thumps with the built in mp3 player. when i tilt my head left they make the satnav screen dark, and tilt right lighter. when head is straight, the satnav screen is just like everything else when im looking through the oakleys.
 

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Discussion Starter #20
I have found most LCD screens to have their polarisation at about a 45' angle.
My friend and I discussed this and he reasoned that the screen manufacturers do this on purpose: they don't know in which orientation the screen will be used in the final application (portrait or landscape), so they make the polarization 45 degrees so that the screen works in at least 50% brightness in either case.

I guess it comes cheaper than having separate manufacturing pipelines for portrait and landscape screens, and marking them accordingly. :rolleyes:
 
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