Method of generating area light source by scanning, scanning area light source and laser projection television using the same

A light projection television using a scanning area light source, comprising an area light source unit, an image combination unit and an image unit, wherein the area light source unit is used for projecting three monochromatic light beams of R, G and B onto a rotating polygon mirror rotating at high speed, the rotating polygon mirror is a polygon central symmetrical about an axis which is perpendicular to the rotating polygon mirror and passes through the center of the rotating polygon mirror, each plane mirror at the side of the rotating polygon mirror is a reflective mirror, and the reflective mirrors make a slope angle to each other along the axial direction;

• N reflective mirrors are arranged on the rotating polygon mirror, and for the 1st to (N/2)th reflective mirrors, the angle thereof with respect to the axial direction increments an angle value progressively in turn;
• for the (N/2+1)th to Nth reflective mirrors, the angle thereof with respect to the axial direction decrements the same angle value progressively in turn, so that the rotating polygon mirror is plane symmetrical;
• when scanning, after rotating the rotating polygon mirror one round, a round-trip scan is finished, wherein N is an even number;
• the rotating polygon mirror is used for horizontally scanning the light beam to generate a horizontal line, vertically scanning the light beam line by line, accompanying with the rotation of the rotating polygon mirror, the monochromatic light beam emitted from the laser is transformed into a uniform area light source which is refreshed with a predetermined field frequency;
• in such manner, each monochromatic light, after passing through the rotating polygon mirror, is transformed into a uniform area light source without interference;
• the area (plane) light sources finally irradiate onto three spatial light modulators of R, G and B;
• the image combination unit is used for combining three monochromatic images into a color image, wherein three spatial light modulators illuminated by three monochromatic light beams of R, G and B form three channel monochromatic images, which are combined in a combination prism to generate a color image;
• the imaging unit is used for projecting the color image from the combination prism on a screen via an objective lens by taking the color image as an object of the objective lens.