Abstract: Apparatus are provided for driving an LED light source and controlling a light output of the light source over a wide luminance range in response to a luminance input. The apparatus includes: a voltage source having an output configured to couple with the light source, a first input configured to receive the luminance input, and a second input; a photodetector unit configured to logarithmically compress the luminance range and determine a voltage based on a luminance of the light source in the compressed range; a comparator having an input coupled to the photodetector unit and having an output; and, a signal converter having an input coupled to the output of the comparator and having an output coupled to the second input of the voltage source. The voltage source is configured to generate an output signal at the output of the voltage source. The output signal has a frequency and a pulse width based on the luminance input.

Abstract: Methods and apparatus are provided for a backlit display with variable luminance and chrominance. The apparatus comprises i groups of LEDs of different colors and one or more sensors optically coupled to the LEDs. The combined light produced by the LEDs is directed to a transmissive liquid crystal display, preferably through a diffusing layer. The sensors monitor the output Si of each group of LEDs. Si for each group of LEDs is multiplied by a chrominance determining parameter Ki to obtain Ki*Si which is then compared to a commanded luminance signal LC to obtain LC?Ki*Si, which difference is used to adjust the drive current to each group of LEDs to achieve LC with the desired chrominance set by Ki. By changing Ki and LC the chrominance and luminescence of the display may be varied and aging effects compensated.

Abstract: A method and system for pushing information to personal computing and communication devices operated by users in such a way that the users can use and/or act upon the information even when the users are off-network or off-line. The method and system also automatically “provisions” the personal computing and communication devices so that the devices may be used to act upon the information that is pushed to the devices.