Patent ID: 7196687

Claim:
A method for illuminating a liquid crystal panel which has a display area and comprises a plurality of rows which are sequentially addressed during a frame refresh cycle, said frame refresh cycle having a period T and each of the plurality of rows having a predetermined refresh time within the frame refresh cycle with the period of time between successive refresh times for each row being equal to T, said method comprising: (a) providing illumination light from a light source; (b) compressing the illumination light into a stripe which has an area smaller than the display area, said stripe being parallel to the plurality of rows; (c) using a moving optical element to cause the stripe of illumination light to scan over the display area in a direction perpendicular to the plurality of rows, said direction corresponding to the direction in which the plurality of rows tire sequentially addressed during the frame refresh cycle; and (d) synchronizing the scanning of the stripe of illumination light with the frame refresh cycle so tat for each row of the display, the majority of the illumination light which impinges on the row as a result of the scan is in the last half of a refresh period for the row.