Display with sub-region backlighting

• US 20070024772A1
• Filed: 07/28/2005
• Published: 02/01/2007
• Est. Priority Date: 07/28/2005
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Allen, William, Childers, Winthrop
• Application Number:
  US11/191,573
• Publication Number:
  US 20070024772A1
• Time in Patent Office: Days
• US Class Current: 349/68
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

A display includes a matrix of liquid crystal elements, and a plurality of direct backlight devices. Each direct backlight device is configured to selectively illuminate a discrete portion of the matrix of liquid crystal elements associated with a backlighting sub-region with a temporal sequence of at least two illumination color lights during an image frame period.

Claims

1. A display comprising:

a matrix of liquid crystal elements; and

a plurality of direct backlight devices, each direct backlight device being configured to selectively illuminate a discrete portion of said matrix of liquid crystal elements associated with a backlighting sub-region with a temporal sequence of at least two illumination color lights during an image frame period.

2. A display in accordance with claim 1, further comprising:

an optical layer, operatively arranged between the plurality of direct backlight devices and the matrix of liquid crystal elements, and configured for each backlighting sub-region to direct at least a portion of the illumination color lights from the direct backlight device to the corresponding discrete portion of said matrix of liquid crystal elements.

3. A display in accordance with claim 1, wherein each sub-region provides backlighting for a discrete subset of pixel elements of the liquid crystal matrix.

4. A display in accordance with claim 1, wherein the temporal sequence comprises a first sub-frame, during which a first illumination color is generated, and a second sub-frame, during which a second illumination color is generated.

5. A display in accordance with claim 4, wherein a first portion of the subset of pixel elements are in an ON state during the first sub-frame, and a second portion of the subset of pixel elements are in an ON state during the second sub-frame.

6. A display in accordance with claim 4, wherein the temporal sequence further comprises a blank period inserted between the first sub-frame and the second sub-frame, wherein substantially no light is generated by the backlight device.

7. A display in accordance with claim 1, further comprising a blank period following the image frame period, wherein substantially no light is generated by the backlight device.

8. A display in accordance with claim 1, wherein the temporal sequence of illumination colors is selected from the group consisting of red, green, blue, white, cyan, yellow, and magenta.

9. A display in accordance with claim 1, wherein the backlight device comprises an LED device.

10. A display in accordance with claim 9, wherein the LED device comprises an array of LED elements configured to provide multiple illumination colors at a selected intensity level.

11. A display, comprising:

a direct-view spatial light modulator having an array of pixel elements; and

an array of backlighting elements, each backlighting element being associated with a sub-region of the array of pixel elements and configured to provide a temporal sequence of illumination colored light to the associated sub-region of the array of pixel elements.

12. A display in accordance with claim 11, wherein each sub-region provides backlighting for a discrete subset of the pixel elements.

13. A display in accordance with claim 12, wherein the temporal sequence comprises a first sub-frame, during which a first illumination color is generated, and a second sub-frame, during which a second illumination color is generated.

14. A display in accordance with claim 13, further comprising a blank period, inserted into the temporal sequence adjacent to at least one of the sub-frames, wherein substantially no light is generated by the backlighting element associated with a selected sub-region.

15. A display in accordance with claim 13, wherein a first portion of the subset of pixel elements are in an ON state during the first sub-frame, and a second portion of the subset of pixel elements are in an ON state during the second sub-frame.

16. A display in accordance with claim 11, wherein the temporal sequence of illumination colors is selected from the group consisting of red, green, blue, white, cyan, yellow, and magenta.

17. A display device, comprising:

a first higher resolution light modulator, comprising an array of pixel elements configured to provide image information; and

a second lower resolution color light modulator, configured to illuminate the first higher resolution light modulator, comprising an array of independently-addressable color lighting devices, each lighting device configured to provide a temporal sequence of illumination colored backlighting to a sub-region of the higher resolution light modulator, in synchronization with selective actuation of the pixel elements of the higher resolution light modulator.

18. A display device in accordance with claim 17, wherein the first higher resolution image modulator comprises an active matrix LCD display

19. A display device in accordance with claim 17, wherein the second lower resolution color light modulator comprises an array of multi-color LED devices.

20. A display device in accordance with claim 17, wherein the temporal sequence comprises a plurality of sub-frames, each sub-frame representing a temporal portion of an image frame, the lighting devices in each sub-region being configured to generate discrete illumination colors during each sub-frame.

21. A method for displaying an image, comprising the steps of:

dividing an image signal for a single image frame into spatially discrete portions corresponding to a plurality of discrete backlight sub-regions of a direct-view spatial light modulator;

subdividing each spatially discrete portion of the image signal into temporally discrete sub-frames characterized by an illumination color across a range of pixel elements associated with the corresponding backlight sub-region;

modulating the spatial light modulator to sequentially actuate each range of pixel elements during each sub-frame; and

modulating a color backlight device in each sub-region for each sub-frame to sequentially provide the illumination color for each range of pixels for each sub-frame.

22. A method in accordance with claim 21, wherein the step of modulating the color backlight device in each sub-region further comprises generating a first illumination color during a first sub-frame, and generating a second illumination color during a second sub-frame.

23. A method in accordance with claim 21, wherein the step of modulating the color backlight device in each sub-region comprises modulating at least one of the intensity, pulse width, duration, duty cycle, and sequence of color generated by the backlight device.

24. A method in accordance with claim 21, further comprising the step of providing a blank period between consecutive image frames, during which the backlight device generates substantially no light.

25. A method in accordance with claim 21, further comprising the step of providing a blank period between consecutive sub-frames, during which the backlight device generates substantially no light.

26. A method for displaying an image, comprising the steps of:

analyzing an image signal to determine illumination colors and intensities for an image frame for a plurality of spatial sub-regions of a display;

generating a control signal for each sub-region based upon the image signal, the control signal being configured to temporally sequentially actuate a subset of pixels associated with the sub-region during a frame period; and

generating a control signal for a backlight device associated with the sub-region of pixels, so as to temporally sequentially actuate the backlight device to provide a desired illumination color for each subset of pixels for each sub-frame.

27. A method in accordance with claim 26, wherein the control signal is configured to produce a blank period, during which the backlight device generates substantially no light, adjacent to at least one of the image frame and a selected sub-frame.