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  Independent control of light emitting diodes for backlighting of color displaysUSPTO Application #: 20080018830Title: Independent control of light emitting diodes for backlighting of color displays Abstract: Backlighting systems for color display screens include clusters of LED devices of different colors that are configured to radiate the different colors in a light path that impinges on the color display screen, to provide backlighting on the color display screen. LED device controllers are provided, a respective one of which is configured to control operating parameters of a subset of the clusters of LED devices, a single cluster of LED devices and/or individual LED devices in the individual clusters. The LED device controllers may use a common data line. (end of abstract)
Agent: Myers Bigel Sibley & Sajovec, P.A. - Raleigh, NC, US Inventor: Gerald H. Negley USPTO Applicaton #: 20080018830 - Class: 349069000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080018830. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of U.S. application Ser. No. 11/185,397, filed Jul. 20, 2005, entitled Independent Control Of Light Emitting Diodes For Backlighting Of Color Displays, assigned to the assignee of the present application, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein. FIELD OF THE INVENTION [0002] This invention relates to displays such as Liquid Crystal Displays (LCDs), and more particularly, to backlighting of displays such as LCDs. BACKGROUND OF THE INVENTION [0003] Display screens are widely used for computer monitors, televisions and many other consumer and commercial display applications. Some flat panel display screens include an array of optical shutters and a backlight system that impinges light on the display screen. [0004] For example, LCD devices are widely used in flat panel displays for monitors, televisions and other consumer and commercial display applications. As is well known to those having skill in the art, an LCD display generally includes an array of LCD devices that act as an array of optical shutters. Transmissive LCD displays employ backlighting using, for example, fluorescent cold cathode tubes above, beside and sometimes behind the array of LCD devices. A diffusion panel behind the LCD devices can be used to redirect and scatter the light evenly to provide a more uniform display. [0005] Conventional shuttered display devices generally include three different color picture elements (often referred to as pixels and/or subpixels), generally red (R), green (G) and blue (B) picture elements. A backlight system for shuttered display devices may be configured to uniformly radiate light on the display screen that provides the appearance of white light. As used herein, "different colors" means different frequency spectra having different center frequencies. [0006] It is also known to provide an array of fluorescent cold cathode tubes behind and facing the planar array of LCD devices. Unfortunately, an array of fluorescent cold cathode tubes may increase the thickness of the LCD display and/or increase the power consumption thereof. It also may be difficult to uniformly illuminate the planar array of LCD devices with the array of fluorescent cold cathode tubes. [0007] Semiconductor light emitting devices, such as Light Emitting Diode (LED) devices, also may be used for edge illumination of a planar array of LCD devices. For example, U.S. patent application Ser. No. 10/898,608, filed Jul. 23, 2004, entitled Reflective Optical Elements for Semiconductor Light Emitting Devices, to the present inventor Negley, and assigned to the assignee of the present invention, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein, describes side emission LEDs that may be used for large area LCD and/or television backlighting. [0008] LED devices also may be used for direct backlighting of LCD displays. For example, U.S. patent application Ser. No. 11/022,332, filed Dec. 23, 2004, entitled Light Emitting Diode Arrays For Direct Backlighting Of Liquid Crystal Displays, to the present inventor Negley, and assigned to the assignee of the present invention, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein, describes a display panel for a flat panel display that includes a planar array of LCD devices and a planar array of LED devices that is closely spaced apart from the planar array of LCD devices, to provide backlighting for the planar array of LCD devices. [0009] As is well known to those having skill in the art, the electrical and/or optical parameters of individual LED devices that are fabricated may vary considerably, for example, due to routine process variations. In order to provide backlighting uniformity and/or to provide a desired backlighting color point, it may be desirable to sort or "bin" LED devices that are to be used for backlighting applications, to allow close matching of electrical and/or optical parameters of the LED devices. Unfortunately, this binning may produce additional manufacturing complexity and/or may lead to at least some of the LED devices being rejected as being unsuitable. Binning and/or rejection of some LED devices also may increase the resultant cost of LED backlighting systems. SUMMARY OF THE INVENTION [0010] Exemplary embodiments of the invention provide edge and/or direct backlighting systems for color display screens that include an array of color picture elements. These backlighting systems include a plurality of clusters of LED devices of different colors that are configured to radiate light of the different colors in a light path that impinges on the color display screen, to provide backlighting on the color display screen. An LED device controller also is provided that is configured to independently control operating parameters of subsets of the clusters of LED devices. In some embodiments, the LED device controller is configured to independently control the operating parameters of individual clusters of LED devices. In other embodiments, the LED device controller is configured to independently control the operating parameters of individual LED devices in individual clusters of LED devices. In yet other embodiments, the LED device controller is configured to use a common data line. In some embodiments, the operating parameters of the subsets, clusters and/or individual LED devices may be controlled to provide uniform backlighting, by compensating for electrical/optical parameter differences among the LED devices and/or to provide a desired color point of the backlighting, by compensating for electrical/optical parameter differences among the LED devices. [0011] In other embodiments of the present invention, a plurality of LED device controllers is provided, a respective one of which is configured to control operating parameters of a subset of the clusters of LED devices. In other embodiments, a respective LED device controller is configured to control the operating parameters of a single cluster of LED devices, and, in some embodiments, to control the operating parameters of the individual LED devices in the cluster. A common data line also may be used in some embodiments. [0012] Various packaging techniques for edge and/or direct backlight LED devices and LED device controllers may be provided according to various embodiments of the present invention. For example, in some embodiments, a respective cluster of LED devices comprises a red, a blue and a green LED device, and the plurality of LED device controllers comprise a plurality of LED device controller integrated circuits. In some embodiments, a respective cluster comprising a red, a blue and a green LED device is mounted on a respective LED device controller integrated circuit. Multiple LED device controller integrated circuits may be mounted on a mounting substrate. In some embodiments, a reflector also may be provided between a respective cluster of red, blue and green LED devices, and a respective LED device controller integrated circuit. [0013] In still other embodiments, a respective cluster comprising a red, blue and green LED device and a respective LED device controller integrated circuit are mounted on a common substrate. The common substrate may include a reflector adjacent the cluster of LED devices. The common substrates may be mounted on a mounting substrate. [0014] In any of the above-described embodiments, at least some of the LED controller integrated circuits may be electrically connected to a common data line. The plurality of LED device controllers may be configured to control operating parameters of the LED devices, and thereby provide uniform backlighting and/or a desired color point of the backlighting, by compensating for electrical/optical parameter differences among the LED devices. [0015] It will be understood that embodiments of the invention have been described above in connection with edge and/or direct backlight systems for color display screens. However, other embodiments of the present invention can provide backlighting methods for color display screens, wherein operating parameters of subsets of the clusters of LED devices are independently controlled during operation thereof. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIGS. 1-4 are cross-sectional views of color display screens including backlighting systems/methods according to exemplary embodiments of the present invention. [0017] FIGS. 5-7 are perspective views of backlighting systems/methods according to exemplary embodiments of the present invention. DETAILED DESCRIPTION [0018] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. However, this invention should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thickness of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout. As used herein the term "and/or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as "/". Continue reading... Full patent description for Independent control of light emitting diodes for backlighting of color displays Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Independent control of light emitting diodes for backlighting of color displays patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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