It’s hot, it’s sunny and you want to spend the day outside. But as soon as you put your sunglasses on, your phone screen goes blank. What’s going on?
Well, there’s nothing wrong with your phone, it’s just that your expensive polarised sunglasses don’t play nice with your smartphone’s screen.
The screen on your phone has a polarising filter that helps to cut glare and reflections, ironically to make it easier to see in bright sunlight. The problem is, your shiny new sunglasses also have a polarising filter to cut glare from shiny surfaces (which is really handy when driving).
When the filters are aligned in opposite directions, all the light from your screen is cut out so you can’t see anything.
Which phones have the problem?
All polarised sunglasses have their filters aligned vertically. This means that light coming off of horizontal surfaces, like a wet road or lake, doesn’t create blinding glare.
Phones, however, don’t all have the same filters. When you hold a HTC One M9 or Sony Xperia Z3 in portrait, for example, the filter is aligned vertically so you’ll see the screen perfectly through your sunglasses. But when you turn the phones landscape, like when you’re taking a photo, the screens dim dramatically.
The Samsung Galaxy S6, iPhone 6 and Microsoft Lumia 640 all have their polarising filters aligned at a 45-degree angle, so you’re unlikely to ever notice a problem. But that does mean their screens don’t seem as bright when you’re not wearing sunglasses, so it’s not all plain sailing.
As different phones use the filters differently, it might be worth taking your sunglasses with you next time you go looking for a new phone if you’re particularly worried about the problem.
What can you do about it?
If you don’t want to buy a phone just because its polarising filter is the right way round, there is something you can do.
Screen protectors often cancel out the effects of your phone’s filter, so you’ll be able to wear your sunglasses and keep your phone’s screen looking like new.