In recent years, the short-focus projector has gradually become a hot spot, and it has quickly gained the love of users in its development. According to IDC's research data, the market share of "short coke" products increased significantly in 2009, with a market share of 2. 1% and a sales volume of about 1.8 million units. It is predicted that the short-focus projector market will grow substantially in 20 10, with a market share of 4.4% and sales exceeding 40,000 units. Short-focus technology has developed from the initial educational application to a wider application level such as office business, entertainment and games, and shows a broad development space. Short-focus projectors need less distance, often only a few tens of centimeters, which can project a larger picture in a shorter distance. The short-focus projector is also very convenient to install, just put it in front of the projection screen. Compared with the traditional projector which can only be installed in the middle of the roof, it has the advantages of saving space and convenient installation. At present, the short-focus projection products on the market can project a picture of more than 100 inch within a distance of about 1.8 meters, which can fully meet the needs of users in small spaces.