The double scan assures flicker-free picture which makes viewing TV easier and gentler to your eyes. The human eye is usually sensitive when the picture flickers at this speed. These are basically a colour carrier for the picture. It is an information service broadcasting by the TV stations via the local TV channel. Information such as weather forecasts and news is available at any time.
Most manufacturers now promote their televisions with flat screens.
When looked at from a closer range, some screens are indeed flatter in the center of the screen than full-spherical tubes. Some are flat from top to bottom, including the corners. This presents a cleaner, bigger video impression in the same size screen and also less geometric distortion and reflects ambient room light downward and away from your eyes. If you want to check the screen, take a flat edge and drag it across the screen to see if the set that you are testing is truly flat. The best picture is not the result of a flat screen alone.