The purpose of LCD is to protect eyes, provided that there is a high-definition signal, otherwise the effect is not as good as CRT! The rear projection uses three small picture tubes to cast an influence on the glass itself, then magnifies it with a magnifying glass, and finally displays it through a layer of plexiglass. It is characterized by a large figure and enjoyable to watch. The disadvantage is that the clarity is not enough! Flat pipes are not much different from ordinary pipes. The difference is that the surface is flat. The advantage is to make the picture look more neat and closer to the scenes seen by the eyes in life. Ordinary flat tube has no advantage, but it can read people, not clear!