Patent attributes
LED calibration systems and related methods are disclosed that use the photo-sensitivity of LEDs to correct for variations between LEDs during initial production and over the lifetime of systems using LEDs. The disclosed systems and methods include methods to set the color or color temperature produced by a group of LEDs during the manufacturing of a device such as a lamp, an LED display, or an LCD backlight, and maintaining such color or color temperature over the operating life of such a device. The methods involve measuring the intensity and/or wavelength of light produced by each LED within a group of LEDs and adjusting an amount of light generated by the LEDs to produce precise color and intensity from the group of LEDs. Two methods that operate some of the LEDs in photovoltaic or photoconductive mode to measure the light intensity produced by other LEDs in the group are presented. The first method uses an additional light source as a reference and determines the light intensity emitted from each LED relative to such reference, while the second method determines the light intensity emitted from each LED relative to each other.
