Tatsuo Saishu

30.3: Autostereoscopic Partial 2-D/3-D Switchable Display Using Liquid-Crystal Gradient Index Lens

We developed 12-inch 9-view autostereoscopic partial 2-D/3-D switchable display using liquid crystal gradient index (GRIN) lens. We simulated optically by the stacked refraction-index distribution model and optimized liquid crystal (LC) material and electrode structure. The prototype achieved wide viewing angle and good 3-D image quality with mosaic color filter and vertical lens.

53.3: Distortion Control in a One-Dimensional Integral Imaging Autostereoscopic Display System with Parallel Optical Beam Groups

We have developed a one-dimensional integral imaging auto-stereoscopic display system consisting of an FPD and a lenticular plate that creates parallel optical beam groups. The reproduced 3-D images are free of distortion and show smooth motion parallax. We describe the methods employed for projection, elemental image alignment, and distortion control.

Novel viewing zone control method for computer-generated integral 3-D imaging

We propose a novel algorithm to maximize the viewing zone of integral 3-D imaging (II) display. In our algorithm, the elemental image array consists of two kinds of elemental images whose numbers of sub-pixels are N and (N+1). The pitch of exit pupils was set to be N times the width of the sub-pixel and an average width of elemental images was designed to exceed the pitch of the exit pupils to a small extent by distributing the elemental images consisting of (N+1) sub-pixels. Under this condition, all light rays generated from elemental images can be introduced to the viewing zone width (viewing width) on the viewing line at the distance L without converging points of light rays at around L. This algorithm was applied to one-dimensional II system with 32 parallax light rays using a 20.8”-QUXGA-LCD (192 ppi) equipped with a lenticular sheet. Then, the viewing width at 1.5 m was expanded to 500 mm, a value almost five times larger than the width of a conventional display system. Even if hardware configurations are fixed, our algorithm enables a viewing zone to be the maximum at a certain L.

Autostereoscopic liquid crystal display using mosaic color pixel arrangement

We have developed some prototypes of a one-dimensional integral imaging (1-D II) autostereoscopic display. Generally, II is one of the most promising methods for realizing an autostereoscopic display. However, a lens or barrier pitch is wide and obtrusive because this method requires many parallaxes. In this case, slanting lens or barrier is undesirable because the pattern is asymmetrical. From the result of examination about the display resolution of the autostereoscopic display, we adopted an LCD with mosaic color filter arrangement and a vertical lenticular sheet. We changed the color filter to the mosaic arrangement for two types of LCD. One was an LCD of 20.8-inch diagonal size with QUXGA resolution (3200 x 2400 pixels) and another was an LCD of 15.4-inch diagonal size with WUXGA resolution (1920 x 1200 pixels). The typical specifications of the prototypes of the autostereoscopic display were 32 parallaxes with 300 horizontal resolution for the 20.8-inch size and 18 parallaxes with the same resolution for the 15.4-inch size. We confirmed these prototypes showed good appearance and stereoscopic display properties due to the symmetrical lens pattern.

Effect of light ray overlap between neighboring parallax images in autostereoscopic 3D displays

A display system with lens arrays at the front of a high-resolution LCD has been known as a method to realize an autostereoscopic three-dimensional (3D) display. In these displays, a light ray overlap between neighboring parallax images affects the image quality. In this study, the overlap effects were investigated for the one-dimensional (horizontal parallax only) integral imaging (1D-II) method. We fabricated samples of 1D-II displays with different levels of light ray overlaps and evaluated the 3D image by subjective assessment. It is found that the 1D-II display utilizing the proper parallax overlaps can eliminate banding artifact and have good 3D image quality within the wide range of a viewing area.

Flatbed-type auto stereoscopic display systems using integral imaging method

We have developed a new display technology that allows 3-D images to be viewed on a flatbed display without any need for special glasses. Viewing the display from an angle allows the viewer to experience 3-D images that stand out several centimeters from the surface of the display. By employing the integral imaging method, easy-to-view, natural, and less-fatiguing stereoscopic images were observed. The new technology opens up new areas of application for 3-D displays, including arcade games, e-learning, simulations of buildings and landscapes, and even 3-D menus in restaurants

Resolution analysis of lenticular-sheet 3D display system

We analyzed resolution characteristics of a lenticular-sheet 3D display system. The measured samples are onedimensional integral imaging (1D-II) display systems of 9-18 parallaxes with slanted/vertical lenticular sheet. The measured contrast ratio curves of various sinusoidal patterns as functions of depth are in good agreement with the theoretical resolution limit for both vertical and slanted lenticular-sheet types. The 1D-II display systems with parallel beam configuration show spatial distribution of resolution in the horizontal direction corresponding to parallax crosstalk. If the parallax crosstalk is not designed properly, this distribution is observed as moiré pattern and degrades 3D image quality. When the gap between the lenticular sheet and the elemental image plane changes in the depth direction, the apparent resolution curve shifts in the same direction; if the gap is large, objects displayed at the near side have higher resolution, and if the gap is small, objects displayed at the far side have higher resolution. This phenomenon is also explained by an effect of the parallax crosstalk caused by defocusing.

Orientations and viewing angle dependence of twisted ferroelectric liquid crystal

Abstract Orientations of liquid crystal for TFLC could be controlled by selecting sign of Ps, polarity of alignment layers and rubbing directions. Characteristic viewing angle dependencies of transmittance based on the declined orientation of liquid crystal could be observed for the cell with uniform orientation.

Flatbed-type autostereoscopic display system and its image format for encoding

We have developed a flatbed-type autostereoscopic display system showing continuous motion parallax as an extended form of a one-dimensional integral imaging (1D-II) display system. The 1D-II display architecture is suitable for both flatbed and upright configurations. We have also designed an image format specification for encoding 1D-II data. In this parallax image array format, two (or more) viewpoint images whose viewpoint numbers are separated by a constant number are paired, and all of the paired images are combined to obtain an image the same size as the elemental image array. By using the format, 3-D image quality is hardly degraded by lossy codec. The conversion from this format to the elemental image array is simple and does not depend on changes in the viewing distance and associated changes in camera number. Decoding and converting speeds are sufficiently high due to utilization of middleware based on DirectX.

Flatbed-type 3D display systems using integral imaging method

We have developed prototypes of flatbed-type autostereoscopic display systems using one-dimensional integral imaging method. The integral imaging system reproduces light beams similar of those produced by a real object. Our display architecture is suitable for flatbed configurations because it has a large margin for viewing distance and angle and has continuous motion parallax. We have applied our technology to 15.4-inch displays. We realized horizontal resolution of 480 with 12 parallaxes due to adoption of mosaic pixel arrangement of the display panel. It allows viewers to see high quality autostereoscopic images. Viewing the display from angle allows the viewer to experience 3-D images that stand out several centimeters from the surface of the display. Mixed reality of virtual 3-D objects and real objects are also realized on a flatbed display. In seeking reproduction of natural 3-D images on the flatbed display, we developed proprietary software. The fast playback of the CG movie contents and real-time interaction are realized with the aid of a graphics card. Realization of the safety 3-D images to the human beings is very important. Therefore, we have measured the effects on the visual function and evaluated the biological effects. For example, the accommodation and convergence were measured at the same time. The various biological effects are also measured before and after the task of watching 3-D images. We have found that our displays show better results than those to a conventional stereoscopic display. The new technology opens up new areas of application for 3-D displays, including arcade games, e-learning, simulations of buildings and landscapes, and even 3-D menus in restaurants.