Why screens always display in BLACK color

Why are screens black when turned off?

If you watch TV, for example "Knowledge makes you ah!", You not only learn a lot, but you also see lots of colorful moving pictures. As soon as you turn off the TV, the screen goes black. Pretty achromatic!

Why is that so?

To do this, you first have to know how seeing works in the first place. In the white light of the sun or a lamp, all the colors of the rainbow are contained in the form of light waves. When the white light hits an object, certain colors are reflected or swallowed, depending on its nature.

What is reflected hits our eyes, is detected there in the retina by certain nerve cells and passed on as a signal to the brain. Only then does a color impression arise for us. If an object reflects all the light waves, it appears white to us. If an object does not reflect any light waves, i.e. if it swallows all light waves, it appears black to us.

And what's up with the black TV screen now?

Quite simply: black has the property of not influencing colors any further. Put simply, when watching television, the colors come out of the screen as rays of light and hit our eyes. For example, if the screen were pink, the light that hits the television from outside would also reflect pink to us.

Together with the rays of light that the television screen sends, we would receive a television picture that has a pink tinge. It would be the same with any other screen color. Another color would still be reflected, which would change the actual image. Only black has the property that GAR does not reflect light from outside. Therefore, an unadulterated television picture can only be produced with a black screen. Otherwise the color of the screen would mix in a color cast. Ah!