Synchronized light emitting diode backlighting systems and methods for displays

• US 7,358,954 B2
• Filed: 04/04/2005
• Issued: 04/15/2008
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Brightplus Ventures LLC (IPValuation Partners, LLC)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Negley, Gerald H., Van de Ven, Antony P.
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): LEE JR, KENNETH B
• Application Number:
  US11/098,085
• Publication Number:
  US 20060221044A1
• Time in Patent Office: 1,107 Days
• Field of Search: 345/102, 315/61, 315/69
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• 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

Abstract

A display screen includes at least two arrays of at least two different color picture elements. A backlighting system for the display includes at least two arrays of Light Emitting Diode (LED) devices that are configured to radiate light of at least two colors in a light path that impinges on the display screen, to provide backlighting on the display screen. A synchronizer is configured to synchronously activate and deactivate at least a first one of the arrays of LED devices and at least a first one of the arrays of color picture elements. Different arrays of synchronously activated and deactivated LED devices and color picture elements also may be alternatingly synchronously activated and deactivated. The backlighting also may be pulsed.

Claims

1. A backlight system for a display screen that includes an array of Liquid Crystal Display (LCD) devices including arrays of red, green and blue color filters thereon to provide red, blue and green color picture elements, the backlight system comprising:

arrays of red, green, blue and cyanine Light Emitting Diode (LED) devices that are configured to radiate light of red, green, blue and cyanine colors in a light path that impinges on the display screen to provide backlighting on the display screen; and

a synchronizer that is configured to synchronously activate and deactivate the arrays of green and blue LED devices and the arrays of green and blue color picture elements and to alternatingly synchronously activate and deactivate the array of cyanine LED devices and the arrays of red, green and blue color picture elements.

2. A backlight system according to claim 1 wherein the synchronizer is configured to activate and deactivate at least a first one of the arrays of LED devices multiple times in synchronism with a single activation and deactivation of at least a first one of the arrays of color picture elements.

3. A backlight system according to claim 1 wherein the synchronizer is configured to pulse at least a first one of the arrays of LED devices multiple times in synchronism with a single activation and deactivation of at least a first one of the arrays of color picture elements.

4. A backlight system according to claim 1 further comprising an array of amber LED devices that is configured to radiate light of amber color in the light path that impinges on the display screen to provide backlighting on the display screen and wherein the synchronizer is further configured to synchronously activate and deactivate the arrays of green and blue LED devices and the arrays of green and blue color picture elements and to alternatingly synchronously activate and deactivate the arrays of cyanine and amber LED devices and the arrays of red, green and blue color picture elements.

5. A backlight system according to claim 1 wherein the synchronizer is further configured to synchronously activate and deactivate the array of green LED devices and the array of green color picture elements, to alternatingly synchronously activate and deactivate the array of blue LED devices and the array of blue color picture elements and to alternatingly synchronously activate and deactivate the array of cyanine LED devices and the arrays of red, green and blue color picture elements.

6. A backlight system according to claim 1 further comprising an array of amber LED devices that is configured to radiate light of amber color in the light path that impinges on the display screen to provide backlighting on the display screen and wherein the synchronizer is configured to synchronously activate and deactivate the array of green LED devices and the array of green color picture elements, to alternatingly synchronously activate and deactivate the array of blue LED devices and the array of blue color picture elements and to alternatingly synchronously activate and deactivate the array of cyanine and amber LED devices and the arrays of red, green and blue color picture elements.

7. A display screen comprising the array of LCD devices including arrays of red, green and blue color filters thereon and a backlight system according to claim 1.

8. A method of increasing a color gamut of a display panel that includes a display screen comprising an array of Liquid Crystal Display (LCD) devices including arrays of red, green and blue color filters thereon to provide red, blue and green color picture elements and arrays of red, green, blue and cyanine Light Emitting Diode (LED) devices that are configured to radiate light of red, green, blue and cyanine colors in a light path that impinges on the display screen to provide backlighting on the display screen, the method comprising:

synchronously activating and deactivating the arrays of green and blue LED devices and the arrays of green and blue color picture elements and alternatingly synchronously activating and deactivating the array of cyanine LED devices and the arrays of red, green and blue color picture elements.

9. A method according to claim 8 further comprising activating and deactivating at least a first one of the arrays of LED devices multiple times in synchronism with a single activation and deactivation of at least a first one of the arrays of color picture elements.

10. A method according to claim 8 further comprising pulsing at least a first one of the arrays of LED devices multiple times in synchronism with a single activation and deactivation of at least a first one of the arrays of color picture elements.

11. A method according to claim 8 wherein the display screen further comprises an array of amber LED devices that is configured to radiate light of amber color in the light path that impinges on the display screen to provide backlighting on the display screen and wherein synchronizing further comprises synchronously activating and deactivating the arrays of green and blue LED devices and the arrays of green and blue color picture elements and alternatingly synchronously activating and deactivating the arrays of cyanine and amber LED devices and the arrays of red, green and blue color picture elements.

12. A method according to claim 8 wherein synchronizing further comprises synchronously activating and deactivating the array of green LED devices and the array of green color picture elements, alternatingly synchronously activating and deactivating the array of blue LED devices and the array of blue color picture elements and alternatingly synchronously activating and deactivating the array of cyanine LED devices and the arrays of red, green and blue color picture elements.