Patent ID: 7847764

Claim:
A method for controlling and compensating aging in an LED device comprising the steps of: a) measuring a performance change in light output of the LED device; b) controlling the LED device with a first compensation algorithm derived from the measured performance change, during a first period, to effect a luminance change over time in the light output of the LED device; and c) controlling the LED device with a second compensation algorithm, derived from the measured performance change, different from the first compensation algorithm, during a second period, to effect a second luminance change over time in the LED device's light output; wherein the second luminance change over time in the second period is different from the first luminance change over time in the first period; wherein the first and second periods together are less than the lifetime of the LED device and wherein either step of controlling the LED device restricts the current, voltage, or power supplied to the LED device to less than that necessary to maintain a constant luminance over time.