Led-based LCD backlight with extended color space
First Claim
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1. A backlight for a liquid-crystal display, comprising:
- a first light-emitting diode (LED) array that provides light with a first chromaticity;
a second LED array that provides light with a second chromaticity that is different from the first chromaticity, wherein the second LED array includes at least one LED;
a combining element that combines the light from the first LED and second LED arrays and directs the combined light toward the liquid crystal display; and
a control system that is operationally connected to the second LED array, wherein the control system selectively varies the brightness of the at least one LED independent of the brightness of the first LED array, thereby adjusting the chromaticity of the combined light, wherein the control system includes a processor that calculates the difference between a target chromaticity of the combined light and an actual chromaticity of the combined light, the control system selectively varying the brightness of the at least one LED to reduce said difference.
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Abstract
A backlight for a liquid-crystal display is disclosed. The backlight includes a first LED array that provides light with a first chromaticity and a second LED array that provides light with a second chromaticity. A combining element combines the light from the first LED array and the second LED array and directs the combined light toward the liquid crystal display. A control system is operationally connected to the second LED array. The controller adjusts the brightness of at least one LED in the second LED array to thereby adjust the chromaticity of the combined light.
308 Citations
16 Claims
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1. A backlight for a liquid-crystal display, comprising:
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a first light-emitting diode (LED) array that provides light with a first chromaticity;
a second LED array that provides light with a second chromaticity that is different from the first chromaticity, wherein the second LED array includes at least one LED;
a combining element that combines the light from the first LED and second LED arrays and directs the combined light toward the liquid crystal display; and
a control system that is operationally connected to the second LED array, wherein the control system selectively varies the brightness of the at least one LED independent of the brightness of the first LED array, thereby adjusting the chromaticity of the combined light, wherein the control system includes a processor that calculates the difference between a target chromaticity of the combined light and an actual chromaticity of the combined light, the control system selectively varying the brightness of the at least one LED to reduce said difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A backlight for a liquid-crystal display, comprising:
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a first light-emitting diode (LED) array that provides light with a first chromaticity;
a second LED-array that provides light with a second chromaticity that is different from the first chromaticity, wherein the second LED array includes at least one LED;
a combining element that combines the light from the first LED and second LED arrays and directs the combined light toward the liquid crystal display; and
a control system that is operationally connected to the second LED array, wherein the control system selectively varies the brightness of the at least one LED independent of the brightness of the first LED array, thereby adjusting the chromaticity of the combined light, wherein the control system includes a brightness-measuring means that measures the brightness of at least one of the first and second LED arrays at two predetermined times, the control system selectively varying the brightness of the least one LED of the second LED array in response to a difference in the brightness measured at the two predetermined times, thereby adjusting the chromaticity of the combined light.
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14. A method of adjusting the chromaticity of an LCD backlight, the LCD backlight providing light combined from a first light-emitting diode (LED) array and a second LED array, the method comprising:
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obtaining a target chromaticity for the LCD backlight by measuring the brightnesses of the first and second LED arrays;
determining an actual chromaticity of the LCD backlight;
calculating a difference between the target chromaticity and the actual chromaticity by determining the change in the ratio of the brightnesses of the first and second LED arrays as measured at two predetermined times; and
adjusting the brightness of at least one LED in the second LED array, thereby changing the chromaticity of the light combined from the first and second LED arrays and decreasing the difference between the target chromaticity and the actual chromaticity. - View Dependent Claims (15, 16)
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Specification