Evaluation of Advanced Automotive Interior Lighting using “Pixelated” RGB LEDs

Future cars with (semi-) autonomous driving will have interior lighting with theater-like effects. Such systems consists of “backlighted” light guides with RGB LEDs every ~30 mm (up to 1,000 per car in future); this results in high data rates of RGB grey level data. As such light guides are also used for visualization of the autonomous driving mode, daylight performance, dimming range (night) and advanced security methods are required. Uniformity (homogeneity) of both luminance and color is mandatory for premium visual ergonomics. We examined different approaches from today’s LIN-based single RGB module design, the consumer electronics (CE) WS2812B system and the newly introduced ISELED system, which is optimized for automotive. Our finding are that LIN bus is not effective for pixelated RGB lighting due to limited data rate. We measured for WS2812B and ISELED temperature dependency and spectra. As WS2812B is intended for CE, its color changes with temperature while it is constant for the ISELED due to internal temperature sensor and compensation. New methods based on Contrast Sensitivity Function were applied towards easy implementable requirements for end-of-line test.