Matheson Keys Daffer & Kordzik PLLC
LED illumination device and method for accurately controlling the intensity and color point of the illumination device over time
An illumination device and method is provided herein for controlling an LED illumination device, so that a desired luminous flux and a desired chromaticity of the device can be maintained over time as the LEDs age. According to one embodiment, the method determines an expected wavelength value and an expected intensity value for each emission LED included within the illumination device at the drive current currently applied to the emission LED and the present emitter forward voltage. In addition, the method determines a photodetector responsivity for each emission LED at the expected wavelength value and the present photodetector forward voltage. The photodetector responsivity calculated for each emission LED is used as a reference for adjusting the lumen output of the emission LED to account for LED aging affects.
Ketra, Inc.
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Alcides Jose Jason E.
Dias Lewis