Exterior displays for autonomous cars: techniques, challenges and solutions

Karlheinz Blankenbach; Nadine Nowak; Steffen Reichel

doi:10.1117/12.2606887

3 March 2022 Exterior displays for autonomous cars: techniques, challenges and solutions

Karlheinz Blankenbach, Nadine Nowak, Steffen Reichel

Proceedings Volume 12024, Advances in Display Technologies XII; 1202406 (2022) https://doi.org/10.1117/12.2606887
Event: SPIE OPTO, 2022, San Francisco, California, United States

Abstract

Autonomous cars should communicate by exterior displays with other road users to increase safety. Examples are the visualization of the driving mode and a pedestrian waiting at a crosswalk being informed that the autonomous car will stop. Such displays must be sunlight readable and smoothly integrated into the front and rear of a car. We prototyped a full-scale mock-up to evaluate RGB LEDs and e-paper regarding optical performance. The display size of 80 cm x 40 cm was chosen accordingEN 12966. We evaluated the reasonable LED pixel pitch as 6 mm, which is about half of the minimum for variable traffic signs. RGB LEDs (~ 100 W/m²), black/white and color e-paper (zero power) were measured with simulated ambient light and judged by subjects regarding legibility, color inversion and color perception. The measurements show a large contrast ratio and gamut for the LED displays. The reflectance of the e-paper was 40% (color) and 50% (monochrome), it's a contrast ratio of about 10:1. The reflectance shows a strong dependency of specular included and excluded measurements. However, the color gamut of e-paper was measured as being small and rated as poor. RGB LEDs with attention-grabbing blinking and high luminance (5,000 cd/m²) as well as high contrast ratio and large gamut were rated best. The best exterior application for e-paper is a digital license plate. The foreground of the e-paper should be black or colored, and the background white. However, this is challenging for car design

Conference Presentation

Citation Download Citation

Karlheinz Blankenbach, Nadine Nowak, and Steffen Reichel "Exterior displays for autonomous cars: techniques, challenges and solutions", Proc. SPIE 12024, Advances in Display Technologies XII, 1202406 (3 March 2022); https://doi.org/10.1117/12.2606887

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