High Dynamic Contrast Display System Having Multiple Segmented Backlight

• US 20090174638A1
• Filed: 05/14/2007
• Published: 07/09/2009
• Est. Priority Date: 06/02/2006
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Higgins, Michael Francis, Brown Elliott, Candice Hellen
• Granted Patent: US 8,605,017 B2
• Time in Patent Office: Days
• US Class Current: 345/88
• CPC Class Codes: G02F 1/133613 characterized by the sequence of light sources
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G02F 2201/52 RGB geometrical arrangements
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 5/06 using colour palettes, e.g. look-up tables

Abstract

In one embodiment, a display system includes a subpixelated display panel and a backlight array of individually controllable multi-color light emitters. When the display panel comprises a multi-primary subpixel arrangement having a white (clear) subpixel, the backlight control techniques allows the white subpixel to function as a saturated primary display color. In another embodiment, the display system may calculate a set of virtual primaries for a given image and process the image using a novel field sequential control employing the virtual primaries. In another embodiment, a display system comprises a segmented backlight comprising: a plurality of N+M light guides, said light guides forming a N×M intersections; a plurality of N+M individually addressable light emitter units, each of said N+M light emitter unit being associated with and optically connected to one of said N+M light guide respectively.

Claims

1. A display system comprising:

a spatial light modulator for displaying an output color image formed from input image color data;

the spatial light modulator substantially comprising a subpixel repeating group including subpixels in a plurality of primary colors;

a plurality of individually addressable colored light emitters disposed as a backlight to provide light for forming the output color image on the spatial light modulator;

each light emitter producing light in one of a plurality of colors; and

controller circuitry for controlling light from the plurality of individually addressable colored light emitters;

the controller circuitry using the input image color data to determine a value for each of the individually addressable colored light emitters such that an output image color in one of the subpixels of the spatial light modulator depends on the color of the light from the light emitters.

2. The display system of claim 1 wherein the plurality of individually addressable colored light emitters produce light in the plurality of primary colors of the subpixel repeating group.

3. The display system of claim 1 wherein the plurality of individually addressable colored light emitters produce light in the saturated primary colors of the subpixel repeating group.

4. The display system of claim 1 wherein the plurality of individually addressable colored light emitters producing light in at least one of the saturated primary colors of the subpixel repeating group is tuned to produce light having a specific range of wavelengths for the saturated primary color.

5. The display system of claim 1 wherein the plurality of individually addressable colored light emitters produce light in red, green, blue and cyan colors.

6. The display system of claim 1 wherein the subpixel repeating group includes a clear subpixel as one of the plurality of primary colors;

and wherein the controller circuitry controls the color of the light from the light emitters such that the clear subpixel functions as a backlight controlled primary color to produce the output color image.

7. The display system of claim 6 wherein the controller circuitry controls the color of the light from the light emitters such that the clear subpixel functions as a first backlight controlled primary color in a first region of the output color image and functions as a second backlight controlled primary color in a second region of the output color image.

8. The display system of claim 1 wherein the controller circuitry performs a peak function operation using the input image color data to produce, for each light emitter in a first color, a peak value of the first color in a region of the input image color data corresponding to a local area of a point spread function support of the light emitter.

9. The display system of claim 1 wherein the controller circuitry further uses the values for each of the individually addressable colored light emitters to produce a low resolution version of the input image color data.

10. The display system of claim 1 wherein the spatial light modulator is a liquid crystal display panel.

11. The display system of claim 1 wherein the plurality of individually addressable colored light emitters comprises an array of light emitting diodes.

12. The display system of claim 1 wherein the input image color data is specified as one of red, green and blue color values, red, green, blue, and cyan color values, red, green, blue, and emerald color values, and YCbCr color values.

13. A display system comprising:

a multi-primary spatial light modulator for displaying an output color image formed from an input signal comprising a frame of color input values;

the frame having a first image resolution;

the spatial light modulator substantially comprising a subpixel repeating group including subpixels in at least four primary colors;

a plurality of individually addressable colored light emitters disposed as a backlight to provide light for forming the output color image on the spatial light modulator;

each light emitter producing light in one of at least four primary colors;

a first gamut mapping operation for converting each color input value to a first multi-primary color signal in the color space of the plurality of individually addressable colored light emitters;

the first gamut mapping operation producing a frame of converted color values;

controller circuitry for filtering the frame of converted color values to produce a frame of filtered color values having a second, lower resolution than the frame of color input values;

the individually addressable colored light emitters displaying the frame of filtered color values;

an interpolation operation for calculating brightness values and color values from the frame of filtered color values at each location of the frame of input color values;

a second gamut mapping operation for converting each color input value to a second multi-primary color signal in the color space of the spatial light modulator using the brightness values and color values calculated by the interpolation means; and

a subpixel rendering operation for filtering the second multi-primary color signal for display on the spatial light modulator at the same time as the individually addressable colored light emitters display the frame of filtered color values.

14. The display system of claim 13 wherein the color input values are specified according to a set of input primary colors, and wherein first gamut mapping operation converts each color input value from the color space of the input primary colors to the first multi-primary color signal in the color space of the plurality of individually addressable colored light emitters.

15. The display system of claim 13 wherein the controller circuitry filters the frame of converted color values using a maximum brightness function that computes a maximum brightness in an area of the frame of input color values overlying a first one of the plurality of individually addressable colored light emitters.

16. The display system of claim 13 wherein the controller circuitry filters the frame of converted color values using one of a sync function and a windowed sync function.

17. The display system of claim 13 wherein the first gamut mapping operation includes a metamer select function for selecting a metamer for the first multi-primary color signal.

18. The display system of claim 13 wherein the interpolation operation uses a point spread function of one of the plurality of individually addressable colored light emitters for calculating brightness values and color values from the frame of filtered color values at each location of the frame of input color values.

19. The display system of claim 13 wherein the subpixel repeating group of the spatial light modulator includes a white (clear) subpixel as one of the at least four primary colors, and includes at least three saturated primary colors;

and wherein the subpixel rendering operation uses the white subpixel as an additional reconstruction point for one of the saturated primary colors.

20. A display system comprising:

a spatial light modulator for displaying an output color image formed from an input signal comprising a set of color input values;

the spatial light modulator substantially comprising a set of individually controllable transmissive elements;

a plurality of individually addressable colored light emitters disposed as a backlight to provide light for forming a color image on the spatial light modulator;

each light emitter producing light in one of a plurality of primary colors;

for a plurality of regions, said regions comprising a set of point spread functions of a set of said light emitter, a first mapping operation for selecting a set of virtual primaries that bound each color input value within each said region, said virtual primaries comprising a plurality of intensities of said plurality of said light emitters within said set of point spread functions;

field sequential control circuitry for controlling the duration and illumination of said virtual primaries over a set of fields comprising an intermediate color signal formed by said light emitters within each said region to produce an intermediate color image onto said spatial light modulator; and

circuitry for controlling said set of transmissive elements within each said region to modulate said intermediate color image to produce said output color image.

21. The display system of claim 20 wherein one of said plurality of regions further comprises one transmissive element upon said spatial light modulator within a set of point spread functions of a set of light emitters.

22. The display system of claim 20 wherein one of said plurality of regions is the entire set of transmissive elements upon said spatial light modulator.

23. The display system of claim 20 wherein said set of virtual primaries is selected to optimize the performance of said display system according to a set of operating criteria.

24. The display system of claim 23 wherein said set of operating criteria comprises at least one of a group, said group comprising:

reducing flicker, reducing power consumption, reducing color breakup, increasing dynamic range, and reducing quantization error.

25. The display system of claim 23 wherein said set of virtual primaries is selected to minimize the difference of luminance of said virtual primaries.

26. The display system of claim 23 wherein said field sequential control circuitry controls the duration and illumination of said virtual primaries to optimize the performance of said display system according to a set of operating criteria.

27. The display system of claim 26 wherein said set of operating criteria comprises at least one of a group, said group comprising reducing out of gamut conditions and reducing power consumption.

28. The display system of claim 20 wherein said circuitry for controlling said set of transmissive elements further comprises selecting a set of coefficient values for each transmissive element to control the modulation of said intermediate color image for each field in which a virtual primary is illuminated.

29. A dynamic field sequential display device comprising:

a backlight, said backlight capable of illuminating a plurality of colors and a plurality of intensities of said colors, said colors and intensities of said colors being independently reproducible across a set of regions forming the backlight;

control circuitry for dynamically selecting the color and intensity of the backlight at a given region, said selection dependent upon input color values within said region.

30. The dynamic field sequential display device of claim 29 wherein said plurality of colors further comprising a set of virtual primaries, said virtual primaries selected depending upon said input color values and to optimize the performance of the display system according to a set of operating criteria.

31. The display system of claim 30 wherein said set of operating criteria comprises at least one of a group, said group comprising:

reducing flicker, reducing power consumption, reducing color breakup, increasing dynamic range, reducing quantization error and reducing out of gamut conditions.

32. A display system comprising:

a backlight outputting light in accordance with a first control signal, said backlight comprising;

a plurality of N+M light guides, wherein N light guides disposed in a first direction and M light guides disposed a second direction, said light guides overlapping and forming a N×

M set of optically communicating intersections;

a plurality of N+M individually addressable light emitter units, each of said N+M light emitter unit being associated with and optically connected to one of said N+M light guide respectively;

each light emitter unit capable of producing broad spectrum light for in one of a plurality of colors;

a spatial light modulator for displaying an output color image, said spatial light modulator receiving light from said backlight and modulating said light in accordance to a second control signal; and

controller circuitry for providing said first signal and said second signal, said controller circuitry receiving input color image data and determining said first and said second control signals and outputting said first signal to said plurality of individually addressable light emitter units and outputting said second control signal to said spatial light modulator such that the combination of said light from said backlight and modulated by said spatial light modulator produces an output image based upon said input color image data.

33. The display system of claim 32 wherein said light emitter units comprise broad spectrum CCFL tubes.

34. The display system of claim 32 wherein said light emitter units comprise broad spectrum LED emitters.

35. The display system of claim 32 wherein said light emitter units comprise a set of individually addressable colored LED emitters, said set capable of emitting broad spectrum light.

36. The display system of claim 32 wherein said spatial light modulator comprises a monochrome LCD display.

37. The display system of claim 32 wherein said spatial light modulator comprises a multiprimary LCD display, said multiprimary LCD display further substantially comprises a plurality of a subpixel repeating group, said group further comprising a set of colored subpixels.