Quote:
Originally Posted by viceant
Ok, thanks for the lesson. But, as you say, we don't know yet whether LCD light causes poor eyesight or another health issue. I do prefer e-ink, but it's only my preference.
|
The LED lighting inherently has blue which is bad for the retina and suppresses sleep. It pretty much is clear that too much tablet time, especially at night, is bad for you.
Now eink can have a frontlight. Older ones are "white LEDs" like LCD, however you can turn it off.
The "night" colour of LCDs is done by varying the LCD, not the "White LED" backlight. White LEDs are a composite device, they are really Blue/Violet/UV (depending on cost) with a yellow phosphor. With age there is less yellow. Hence cheaper LCD backlights can look a little purple and all go more violet/purple with age. Conversely my 2000 and 2002 Laptops (which I still have) use CCFL which are a kind of mercury vapour discharge tube giving off mostly UV. They use a much thicker phosphor than LEDs and also a mix of phosphors to better simulate a full spectrum. The blue phosphor (not usually present on LEDs as they are blue) wears faster as on Plasma TVs, so they develop a yellow cast. Our older HDTV is also CCFL, the newer one is LED backlit. Cheaper TVs use LEDs only at the edge.
Newer "comfort" front lights don't use the nasty "white" LEDs, or at least not solely, the colour is achieved by different colours of LED. Some might use RGB LEDs which are Red, Green and Blue chips in one package. A Spectrometer or a prism would tell as RGB LED have 3 spikes. A White LED has a diffuse band from reddish-orange to yellow-green, peaking in yellow and a blue peak. Most have no cyan.
The new filament style LED room lamps are interesting. Each stick is about 20 to 26 LEDs. The power is low per LED so more efficient and phosphor coating works better and ages slower. The entire stick is coated with the yellow phosphor to convert enough blue/violet/UV light. Also the better colour ones have some other colours of LED on the stick (red and cyan) to improve colour rendition. Reading an eink illuminated by these is much better than LCD or OLED screens because there is almost no UV and less blue than regular "White" LEDs. The spectrum is closer to a halogen than traditional LED lamp or even a Fluorescent lamp (tube or CFL or CCFL). Another benefit of the LED stick filaments is that each stick is about 55V. Thus 2 sticks about 110V and 4 sticks 220V. No SMPSU is needed, which generates heat, has lower life than LEDs and usually creates radio interference. So some stick filament LED lamps will also work on dimmers.
So if you have a suitable ambient light / bedside lamp, it's a fact that eink is better for the retina and your sleep patterns than LCD and most OLED phones/tablets.
Nothing to do with placebo.
It's also true that all LCDs have only one polarisation of light, OLED and LCD have narrower view angle and light emission than eink. The eink is a milky coloured liquid. Each cell has a number of black balls. It's got a massive viewing angle, totally diffuse like paper and no polarisation. However there is no evidence I've read that having only one polarisation of light does any harm.