The purpose of this paper is to introduce using scalable autostereoscopic displays that allow users to interact with floating images publicly, such as for digital signage. By tiling multiple display modules, it is possible to project larger autostereoscopic images in the air than by displaying it using a single display module. By projecting autostereoscopic images, it is possible for the user to understand the contents in better detail compared to a standard 2D public displays. Furthermore, by projecting floating images, it is possible to reduce the spatial divergence between the user's body and the autostereoscopic images, so that the user can interact intuitively with autostereoscopic images. Moreover, since this system has scalability, it is possible to expand the screen size just by adding more display modules. This expandability makes the system easy to move and arrange in public spaces. In this paper, we propose an autostereoscopic display module which can enlarge the screen size in the horizontal direction as the first step to realizing our concept.