Control method of active parallax barrier and binocular image for glasses-free stereoscopic display according to viewing position

In 3D displays based on parallax barriers, active parallax barriers that can change the barrier pattern according to the viewing position have been proposed to expand the viewing area. However, the production cost increases because the active barrier requires a special LC panel. Therefore, to lower the cost, we propose a glasses-free stereoscopic display using an active parallax barrier of an LC panel with the same specifications as the image LC panel. The ideal image pattern cannot be formed because the minimum control unit of the LC panel is equal to one subpixel. However, by using an image cycle pitch method (ICPM) that periodically increases the horizontal pitch of one pair of binocular images by one subpixel, we can realize the ideal relationship between the average pitch of the binocular image and the barrier pitch. In our previous research, we could make the average pitch match to the ideal pitch on the discrete optimum viewing distances (OVDs), but we could not follow the viewing position between the discrete OVDs. In this paper, we propose the ICPM that can keep the stereoscopic vision even at any viewing position. In order to verify the effectiveness of the proposed method, we made the prototype displays and evaluated them. As a result, we showed the crosstalk ratio could be suppressed low over a very wide range by using the proposed method. Also, we confirmed we could obtain the stereoscopic vision at the viewing distance from 300 mm to 729 mm by a subjective evaluation.