Are Blue-Filtering Screen Protectors a Scam?
April 19, 2015 11:22 PM Subscribe
Do the clear blue-filtering screen protectors for mobile devices actually do anything? An example. I have a few at hand, and they are completely transparent, I think the product is just a plain clear screen protector.
(The reviews on the amazon link are for all screen protectors from that manufacturer, not just the blue-blocking variety.)
It seems to me that since LCDs emit light at only three specific wavelengths, in order to block the blue, the protector would have to be yellow. The plastic is close to perfectly clear, and putting it in front of any light source, including the phone it's meant to fit on, does not change the color balance in any way. Here's a page from a manufacturer purporting to explain how it works. It looks like they're saying they block light under 450 nm. Which makes sense, doing that would block most blue light, and therefore it would look yellow.
The most charitable explanation I can think of is that it blocks blue light lower in wavelength than the blue of the LCD, blocking some of the "junk" that the imperfect LED filters let through, plus UV. But is there really enough light at those wavelengths coming out of the phone to affect sleep?
Am I right about this? Are these things basically audiophile-style placebo effects? Or is there some aspect of this that I'm overlooking? The reviewers of this product seem similarly uncertain, but amusingly unconcerned.
(The reviews on the amazon link are for all screen protectors from that manufacturer, not just the blue-blocking variety.)
It seems to me that since LCDs emit light at only three specific wavelengths, in order to block the blue, the protector would have to be yellow. The plastic is close to perfectly clear, and putting it in front of any light source, including the phone it's meant to fit on, does not change the color balance in any way. Here's a page from a manufacturer purporting to explain how it works. It looks like they're saying they block light under 450 nm. Which makes sense, doing that would block most blue light, and therefore it would look yellow.
The most charitable explanation I can think of is that it blocks blue light lower in wavelength than the blue of the LCD, blocking some of the "junk" that the imperfect LED filters let through, plus UV. But is there really enough light at those wavelengths coming out of the phone to affect sleep?
Am I right about this? Are these things basically audiophile-style placebo effects? Or is there some aspect of this that I'm overlooking? The reviewers of this product seem similarly uncertain, but amusingly unconcerned.
Well, if you look at an image which has an isolated chunk of blue pixels turned on, like this RGB Color Model, and they don't look dimmer with the filter, then the alleged filter isn't filtering.
Try flux, redshift, or twiglight for ios, MSWin, linux, android, etc. Or those uvex safety googles.
it looks like they're saying they block light under 450 nm.
According to this plot of the eye's response to light vs wavelength, there's a lot of blue we can see under 450 nm. So stuff would look less blue through an actual filter that filtered.
posted by sebastienbailard at 12:19 AM on April 20, 2015 [2 favorites]
Try flux, redshift, or twiglight for ios, MSWin, linux, android, etc. Or those uvex safety googles.
it looks like they're saying they block light under 450 nm.
According to this plot of the eye's response to light vs wavelength, there's a lot of blue we can see under 450 nm. So stuff would look less blue through an actual filter that filtered.
posted by sebastienbailard at 12:19 AM on April 20, 2015 [2 favorites]
wait for a new jailbreak to come out and just install f.lux, and get this effect 100% for sure for $0.
i've had f.lux on my iphone since they were plastic and i was voting for obama the first time around. it works great.
posted by emptythought at 4:12 AM on April 20, 2015 [3 favorites]
i've had f.lux on my iphone since they were plastic and i was voting for obama the first time around. it works great.
posted by emptythought at 4:12 AM on April 20, 2015 [3 favorites]
Best answer: Only thing that actually block blue are yellow filters. If they are transparent, they aren't blocking anything.
As for your idea about LCDs... correct, but how they really work is they have a white backlight shining through colored LCD to produce colored light. (LEDs, such as Samsungs AMOLED screens, are somewhat different).
What you're really buying is a screen protector. Any "filter" capability is just marketing ****.
posted by kschang at 7:47 AM on April 22, 2015
As for your idea about LCDs... correct, but how they really work is they have a white backlight shining through colored LCD to produce colored light. (LEDs, such as Samsungs AMOLED screens, are somewhat different).
What you're really buying is a screen protector. Any "filter" capability is just marketing ****.
posted by kschang at 7:47 AM on April 22, 2015
This thread is closed to new comments.
posted by breath at 11:39 PM on April 19, 2015