The lighting principle of a TV set is basically similar to that of a fluorescent lamp. The electron beam emitted by the electron gun sweeps up layer by layer, so there will be a flashing strong light every time a picture is changed, which is easy to make the eyes tired. If you watch TV too close, it will accelerate eye fatigue. The best distance for people with normal vision to watch TV images is 5 times the diagonal distance of TV screen. For example, if the TV is 20 inches, the viewing distance should be greater than 2.5 meters, and it should not be less than 2 meters recently. If it is difficult to estimate the distance, you can also take the "palm covering method". The method is: one hand is straight forward and the palm is horizontal. If the palm just covers the TV screen, this distance is more appropriate.