Solar projector

Abstract

The sun is the most universal, powerful and familiar energy available on the planet. Every organism and plant has evolved over the years, corresponding to the energy brought by the sun. Humanity is no exception. We have invented many artificial lights since Edison invented light bulbs. In recent years, LEDs are one of the most representative examples. Displays and projectors using LEDs are still being actively developed. However, it is difficult to reproduce ideal light with high brightness and wide wavelength like sunlight. Furthermore, considering low energy sustainability and environmental contamination in the manufacturing process, artificial light can not surpass the sunlight. Against this backdrop, projects that utilize sunlight have been actively carried out in the world. Concentrating Solar Power (CSP) generate electricity using the heat of sunlight to turn turbines [Müller-Steinhagen and Trieb 2004]. [Koizumi 2017] is an aerial image presentation system using the sun as a light source. Digital sundials use the shadow of sunlight to inform digital time [Scharstein et al. 1996]. These projects attempt to use the direct sunlight without any conversion and minimize the energy loss. In this paper, we propose an image projection system using sunlight as a light source (Fig. 1). Specifically, Digital Mirror Device (DMD) reflects concentrated sunlight and projects images with natural light. In this way, it became possible to project images using light in a wide wavelength range that can not be reproduced by LEDs. By directly utilizing sunlight, it is possible to realize new projection harmonious with nature, such as applying it to photosynthesis of plants.