Projection System Components and Principles: 
　1). Device Components: Controlling device, projector and dimmable projection screen. 
　2). Projection Principles: the controlling device consists of output control, power controller and processing unit. Connect projector with output control, dimmable projection screen links with power controller, let output control and power controller establish communication within the controlling device through processing unit, dimmable projection screen changes ON to OFF (in reverse) by controlling the power switches. When the power controller powers on dimmable projection screen, the screen plays as common glass; when the powder is off, it can be used as rear projection screen.
　Wide-angle precision optical projector is recommended, which is 0.233m ultra-short focal distance. 200 inch projection image is easy to achieve when 4500lm projector applied; for 6000lm brightness, larger than 200 inches projection image is enabled like showcase advertising, big new products release conference, cultural transmission company, concerts, exhibitions and other commercial advertising.