Display device which reduces variation in chromaticity of red, blue, and green LEDs
View Patent ↗A display device configured to realize a high display quality by correcting irregularity, caused by a lighting unit, by signal processing. The target light quantity in a displayed image of the liquid crystal panel is set, the estimated light quantity at each pixel location in the plane of the backlight is calculated, matrix coefficients are calculated based on the estimated light quantity and the target light quantity, image signals are subjected to matrix operations using the matrix coefficients, and the liquid crystal panel is driven by image signals resulting from the matrix operations. Therefore, the light quantity distribution in the displayed image becomes identical to the target light quantity distribution.
1. A display device, comprising:
lighting means including a plurality of light emitting devices with different dominant wavelengths in a wavelength distribution;
transmittance control means for enabling a displayed image including a plurality of transmittance control devices for controlling light quantity from said lighting means; and
correcting means for correcting input image signals;
wherein said correcting means includes:
target light quantity setting means for setting a target light quantity on the displayed image at a maximum signals,
estimated light quantity calculating means for calculating an estimated light quantity from light emitting devices at a maximum signal,
matrix coefficient calculating means for calculating matrix coefficients based on said target light quantity and said estimated light quantity, and
matrix operation means for correcting the input image signals by said matrix coefficients and operates said transmittance control means;
wherein a chromaticity distribution of said plurality of light emitting devices is wider than primary colors displayed by said transmittance control devices;
wherein said plurality of light emitting devices have at least three kinds of dominant wavelengths;
wherein said plurality of light emitting devices includes a plurality of red LEDs, a plurality of green LEDs and a plurality of blue LEDs;
wherein a chromaticity of each red LED of said plurality of red LEDs, a chromaticity of each green LED of said plurality of green LEDs and a chromaticity of each blue LED of said plurality of blue LEDs has a variation; and
wherein said matrix operation means reduces changes in chromaticity of the displayed image at said transmittance control means rather than reducing changes in chromaticity of said plurality of light emitting devices at said light emitting means.
2. The display device according to claim 1 , wherein said estimated light quantity calculating means includes first storing means for storing light emission characteristics of each light emitting device; second storing means for storing a light quantity distribution of light emitting devices; and
in-plane distribution calculating means for calculating a light emission distribution of a whole displayed image based on said light emission characteristics and said light quantity distribution, and wherein the display device comprises converting means for multiplying by a non-linear characteristic between said matrix operation means and said transmittance control means.
3. A display device according to claim 1 , wherein said correcting means corrects the input image signals to differentiate between minimum points in a luminance distribution in said lighting means and minimum points in a luminance distribution in said displayed image to thereby eliminate minimum points existing in the luminance distribution of said lighting means.
4. A display device according to claim 1 , wherein said correcting means corrects the input image signals to differentiate between minimum points in a luminance of the dominant wavelengths of said light emitting devices and minimum points in a luminance distribution of said displayed image to thereby eliminate minimum points existing in the luminance distribution of the lighting means.
5. The display device according to claim 1 , wherein said estimated light quantity calculating means includes storing means for storing temperature and elapsed time of said light emitting devices.
6. A display device according to claim 1 , wherein said target light quantity setting means, in a luminance distribution of said transmittance control means in a two-dimensional plane, sets the luminance distribution to be high in a center of said transmittance control means and sets the luminance distribution to be low in a peripheral area of said transmittance control means.
7. A display device according to claim 1 , wherein said matrix operation means sets said chromaticity of said plurality of light emitting devices so that the chromaticity is within ranges of chromaticity distribution which are displayable for said transmittance control means.
8. A display device according to claim 1 , wherein said target light quantity setting means sets light quantity with a convex characteristic in a displayed image, and wherein said matrix operation means drives said transmittance control means by converting the input image signals formed by a plurality of kinds of color signals.
9. A display device according to claim 1 , wherein said estimated light quantity calculating means calculates estimated light quantity at each pixel location by said lighting means, and
wherein the display device further comprises measuring means for transmitting a returned signal for reflecting an operation of said lighting means, to said correcting means.