Directional Backlight Generator for Larger Field Angle Autostereoscopic Display

Abstract

A glasses free directional backlight three-dimensional (3D) display system with an improved directional backlight generator (DBG) is proposed which can provide greater field of view (FOV), more precise control over the direction of the emergent light rays and the improved image uniformity. The directional backlight display system functions by producing regions in the viewing field, referred to as exit pupils where left and right images are seen across the complete area of the screen. The exit pupils are controlled by a head tracker to follow the eyes' positions, eliminating the need to wear special glasses. In previous directional backlight systems, the backlight control is provided by switching groups of LED arrays. This limits the precision of the exit pupil placement and the number of viewpoints. So to overcome these problems an additional liquid crystal display (LCD) panel is used as the amplitude spatial light modulator (SLM). The LCD-SLM panel in this system can be thought as the improved version of the LEDs array in the conventional system. The uniformity of the light energy distribution is improved by introducing an additional set of field lenses. Also, a special way of organizing the position of LEDs is also proposed to further improve the light uniformity. In this paper, we explain how the improvements are implemented and describe the improvements in the uniformity of light energy distribution, especially at larger viewing angles.