Displays with large dynamic range

• US 7,750,887 B2
• Filed: 12/21/2006
• Issued: 07/06/2010
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Bergquist, Johan
• Primary Examiner(s): Patel; Nitin
• Application Number:
  US11/645,018
• Publication Number:
  US 20080150864A1
• Time in Patent Office: 1,293 Days
• Field of Search: 345 87-102, 345/204
• US Class Current: 345/102
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

The specification and drawings present a new method, apparatus and software product for increasing a grey dynamic range of a display for displaying video data by providing a grey level, calculated for a reduced number of primary colors using a predetermined criterion, for each field of a frame set by the display by varying an amplitude or a subfield composition of a display driving signal and by varying a fluence of simultaneously lit backlight sources (e.g., LEDs) corresponding to selected two or more primary colors of the display. Thus, grey level resolution of the display can be increased to match the higher grey level resolution of the video data provided to the display.

Claims

1. A method, comprising:

receiving a video data signal comprising video data;

calculating for each field of a frame set by a display a grey level for expanding a grey dynamic range of the display for displaying said video data for a reduced number of primary colors in said display using a predetermined criterion; and

providing said grey level for said each field by varying an amplitude or a subfield composition of a display driving signal and by varying a fluence of simultaneously lit backlight sources corresponding to selected two or more primary colors of said display.

2. The method of claim 1, wherein said fluence is varied by varying at least one of:

a field duty of said backlight sources and a peak intensity of said backlight sources.

3. The method of claim 1, wherein a fluence ratio of two consecutive fields in said frame is equal to two or one half.

4. The method of claim 1, wherein said display is a field sequential color display.

5. The method of claim 1, wherein said display is a liquid crystal display device or a micro-electro-mechanical systems display.

6. The method of claim 1, wherein said two or more primary colors are red, green and blue.

7. The method of claim 1, wherein said display is a single-hue display.

8. The method of claim 1, wherein said display is a two- or more-primary color display and said calculating and providing are performed for each primary color.

9. The method of claim 1, wherein said backlight sources are light emitting diodes.

10. The method of claim 1, wherein each frame has one or more fields.

11. The method of claim 1, wherein said grey level for said each field is provided by varying said subfield composition of the display driving signal and by varying said fluence by varying said peak intensity of said backlight sources.

12. A computer program product comprising:

a computer readable storage structure embodying a computer program code thereon for execution by a computer processor with said computer program code, wherein said computer program code comprises instructions for performing the method of claim 1, indicated as being performed by a component or a combination of components of an electronic device.

13. An electronic device, comprising:

a controller, configured to receive a video data signal comprising video data for a display, configured to calculate for each field of fields of a frame for primary colors a grey level for expanding a grey dynamic range of said display for displaying said video data for a reduced number of primary colors in said display using a predetermined criterion, and configured to provide said grey level for said each field by varying an amplitude or a subfield composition of a display driving signal and by varying a fluence of simultaneously lit selected two or more primary colors using backlight sources of said display.

14. The electronic device of claim 13, wherein said controller is configured to provide said grey level for said each field by varying said subfield composition of the display driving signal and by varying said fluence by varying said peak intensity of said backlight sources.

15. The electronic device of claim 13, wherein said controller is configured to vary said fluence by varying at least one of:

a field duty of said backlight sources and a peak intensity of said backlight sources.

16. The electronic device of claim 13, wherein a fluence ratio of two consecutive fields in said frame is equal to two or one half.

17. The electronic device of claim 13, wherein said display is a field sequential color display.

18. The electronic device of claim 13, wherein said display is a liquid crystal display device or a micro-electro-mechanical systems display.

19. The electronic device of claim 13, wherein said two or more primary colors are red, green and blue.

20. The electronic device of claim 13, wherein said display is a single-hue display.

21. The electronic device of claim 13, wherein said display is a two or more primary color display and said calculating and providing are performed for each primary color.

22. The electronic device of claim 13, wherein said display comprises said backlight sources and said backlight sources are light emitting diodes.

23. The electronic device of claim 13, wherein each frame has one or more fields.

24. The electronic device of claim 14, wherein said display comprises said field selector and said controller.

27. The electronic device of claim 13, further comprising a field selector, configured to define said fields of the frame for the primary colors.

28. The electronic device of claim 13, wherein said display is a part of the electronic device.

25. An electronic device, comprising:

means for defining fields of a frame for primary colors; and

means for controlling, for receiving a video data signal comprising video data for a display, for calculating for each field of said fields a grey level for expanding a grey dynamic range of said display for displaying said video data for a reduced number of primary colors in said display using a predetermined criterion, and for providing said grey level for said each field by varying an amplitude or a subfield composition of a display driving signal and by varying a fluence of simultaneously lit selected two or more primary colors using backlight sources of said display.

26. The electronic device of claim 25, wherein said selecting means is a field selector.