Swept illumination to reduce LCD lag in front and rear projection displays
First Claim
1. 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 (the cycle refresh period) 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 are sequentially addressed during the frame refresh cycle; and
(d) synchronizing the scanning of the stripe of illumination light with the frame refresh cycle so that 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 the cycle refresh period for the row.
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Accused Products
Abstract
Methods for illuminating the display area of a liquid crystal panel (13) are provided. Illumination light (17) is compressed into a stripe which is scanned across the display area in synchronization with the display'"'"'s refresh cycle. In particular, the scanning is performed so that 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 the cycle fresh period for the row. In this way, the ability to display moving objects is improved.
26 Citations
19 Claims
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1. 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 (the cycle refresh period) being equal to T, said method comprising:
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(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 are sequentially addressed during the frame refresh cycle; and
(d) synchronizing the scanning of the stripe of illumination light with the frame refresh cycle so that 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 the cycle refresh period for the row. - View Dependent Claims (2, 3)
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4. A method for illuminating a display 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 the cycle refresh period for the row and being equal to T, said method comprising:
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(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) sequentially scanning the stripe of illumination light over each of the plurality of rows during the frame refresh cycle; and
(d) synchronizing the scanning of the stripe of illumination light with the frame refresh cycle so that for each row of the display, the majority of the illumination light which impinges on that row as a result of the scan is in the last half of the cycle refresh period for that row. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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12. A display comprising:
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an illumination system comprising a light source, and a movable optical element, wherein the illumination system is capable of compressing light from the light source into a stripe of illumination light that has an area smaller than the display area;
a display panel comprising a display area and a plurality of rows; and
a processor configured and arranged to sequentially address each of the plurality of rows of the display panel during a frame refresh cycle to display an image, wherein the frame refresh cycle has a period T and each of the plurality of rows has a predetermined refresh time within the frame refresh cycle with the period of time between successive refresh times for each row being the cycle refresh period for the row and being equal to T, the processor being further configured and arranged to move the optical element to scan the stripe of illumination light sequentially over each of the plurality of rows in a synchronized manner so that the majority of the illumination light impinges on each row during the last half of the cycle refresh period for that row. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification