Fault tolerant led backlight for an lcd display

Abstract

Disclosed are LED backlight subassemblies and LCD displays making use thereof. The backlight subassembly includes at least one string of serially connected LEDs in which single LED failures do not lead to a partial or complete loss of image content.

What is claimed is: 
     
         1 . An LED illumination subassembly for an LCD display, the LCD display comprising an LCD panel, said subassembly comprising a plurality of LED strings and a plurality of current limiting resistors, each of said LED strings comprising at least two serially connected LEDs connected in series with a respective one of said current limiting resistors, each of said LED strings being arranged in an array, said array being arranged to be disposed adjacent the LCD panel wherein said LEDs of each of said strings of said array extends non-linearly across the LCD panel in a pseudo-random pattern. 
     
     
         2 . The subassembly of  claim 1  wherein each of said LEDs of each of said strings has associated with it at least one respective electronic component arranged to enable the other LEDs of said string to produce light in the event that any LED in said string should fail open. 
     
     
         3 . The subassembly of  claim 2  wherein each of said at least one electronic components comprises a reverse oriented zener diode, and wherein each reverse oriented zener diode shunts a respective LED of said LED string. 
     
     
         4 . The subassembly of  claim 2  wherein each of said at least one electronic components comprises a respective back-up LED connected in series with a respective diode to form a back-up LED path and wherein each back-up LED path shunts a respective LED of said LED string. 
     
     
         5 . An LED illumination subassembly for an LCD display, said subassembly comprising a plurality of LED strings and a plurality of current limiting resistors, each of said LED strings comprising at least two serially connected LEDs connected in series with a respective one of said current limiting resistors, each of said LEDs of each of said strings having associated with it at least one respective electronic component arranged to enable the other LEDs of said string to produce light in the event that any LED in said string should fail open. 
     
     
         6 . The subassembly of  claim 5  wherein said plurality of LED strings is arranged to be disposed in an array adjacent an LCD panel of the LCD display wherein the LEDs of each of said strings of said array extends non-linearly across the LCD panel in a pseudo-random pattern. 
     
     
         7 . The subassembly of  claim 6  wherein each of said at least one electronic components comprises a reverse oriented zener diode, and wherein each reverse oriented zener diode shunts a respective LED of said LED string. 
     
     
         8 . The subassembly of  claim 6  wherein each of said at least one electronic components comprises a respective back-up LED connected in series with a respective diode to form a back-up LED path and wherein each back-up LED path shunts a respective LED of said LED string. 
     
     
         9 . An LCD display comprising an LCD panel and at least one LED illumination subassembly, said subassembly being located adjacent said LCD panel and comprising a plurality of LED strings and a plurality of current limiting resistors, each of said LED strings comprising at least two serially connected LEDs connected in series with a respective one of said current limiting resistors, each said at least two serially connected LEDs of each of said strings having associated with it a respective diode arranged to enable the other LEDs of the string to produce light in the event that any LED in said string should fail open. 
     
     
         10 . The LCD display of  claim 9  wherein said plurality of LED strings is disposed in an array adjacent an LCD panel of the LCD display wherein the LEDs of each of said strings is disposed non-linearly across the LCD panel in a pseudo-random pattern.