Abstract: A light source having a photodetector embedded in a light pipe is disclosed. The light pipe includes a layer of transparent material having top and bottom surfaces and first and second opposing side surfaces that intersect the top and bottom surfaces. In one embodiment, the photodetector is embedded in the layer at a location that is adjacent to the second side surface and a plurality of light emitters are positioned so as to couple light into the layer of material through the first side edge at angles less than or equal to the critical angle for the layer of material. The bottom surface can include protrusions for scattering light toward the top surface. A controller adjusts the intensity of the various light emitters in response to changes in light intensity detected by the photodetector. Light leaving the top surface of the light pipe can be used to illuminate a display.

Abstract: A display and method for displaying data are disclosed. The display includes a light source and a gauge that displays a quantity. The gauge is illuminated by the light source that has a color specified by a first control signal. A controller generates the first control signal based on the quantity such that the light source generates light of a first color if the quantity is within a first range and light of a second color if the quantity is in a second range. In one embodiment, the light source is characterized by an intensity specified by a second control signal, and the controller generates a second control signal based on the quantity such that the light intensity has a first intensity value when the quantity is in a third range and a second intensity value when the quantity is in a fourth range.

Abstract: An LED-based light system includes a primary light source and at least one redundant light source. The primary light source is activated by itself and the performance of the light source is measured to determine whether nor not to drive the redundant light source. The redundant light source is activated when the performance measurements indicate that a performance characteristic is not being met by the primary light source alone. The first light system can be activated in combination with the redundant light source once the decision is made to activate the redundant light source.