US Patent 7777948 Projection screen

A projection screen is disclosed, which includes an upper housing, an upper roller, a reflecting curtain, a lower housing, a lower roller, a lower mask and a positioning assembly. The upper roller is pivoted in the upper housing. The reflecting curtain is wound on the upper roller and has a reflecting surface to form a projection area. The lower housing is fixed at a free end of the reflecting curtain. The lower roller is pivoted in the lower housing. The lower mask is wound on the lower roller. The positioning assembly detachably connects a free end of the lower mask to the reflecting curtain, so that the lower mask covers a portion of the reflecting surface of the reflecting curtain to define the boundary of the projection area.