Reflective vs. light emitting displays

[mrspeedybob]

I was thinking about how my eyes get fatigued after looking at a computer or TV screen for too long and it occurred to me that it takes much longer for them to fatigue when looking at a book. It seems to me that the difference is that a screen emits light whereas a page in a book only reflects light. I'm sure it's possible to create a display that is only reflective and does not emit its own light, thereby reducing eye fatigue.

Do such displays exist? If so, why are they not in wide use? How do they work?

If they don't exist, why not? Is the problem technical or is this just something that nobody wants?

[Studiot]

Here is an interesting adjunct for you to ponder.

Cinema screens are white.

How is black projected onto them, since black is the abscence of light?

[mrspeedybob]

Here is an interesting adjunct for you to ponder.

Cinema screens are white.

How is black projected onto them, since black is the absence of light?

If no light is projected onto a spot on the wall that spot looks black. A surface which reflects no light looks the same as a surface which is un-illuminated.

I see what your getting at and while a theater screen may technically be a reflective display that's not really what I had in mind. It's still a lit display, it's just that it's light is projected onto it from another place. I was thinking of a display which would reflect ambient light like a book page does. This sort of display would not be visible in the absence of ambient light.