Long-Distance Aerial LED Signage for Outdoor Use With AIRR Optics Utilizing a Fresnel Lens

We study aerial displays for outdoor digital signage with aerial imaging by retro-reflection (AIRR) that can be used to provide traffic information. A major challenge for providing outdoor information by means of aerial displays was to ensure brightness. We have developed a light source to form aerial images that meet the luminance requirements for outdoor use. The problems with the light source were insufficient power and optimizing the light distribution angle. These two problems were solved to form an aerial image that could meet the standards for outdoor use. We have tested whether the aerial images are visible outdoors using a prototype with this light source. As a result, the aerial image can be seen with the naked eye from a distance of 100 m away. In addition, we also conducted experiments with artificial sunlight to investigate the effects of direct exposure to the western sunlight. This paper discusses what has emerged from these experiments.