Rieko Fukushima

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

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.

A 15‐in. XGA thresholdless antiferroelectric LCD addressed by TFTs and using the quasi‐dc driving method

— A 15-in. TFT-LCD with XGA resolution using thresholdless antiferroelectric liquid crystal (TLAF) has been developed. TLAF materials show V-shaped switching and enable display of analog gray scale, wide viewing angle, and fast response. However, in the case that high-resolution TFT-LCDs using materials with large spontaneous polarization such as TLAF were driven by the conventional method, alternating current (ac) driving, the obtained contrast ratio was limited because of a sharp decline of holding voltage due to the growth of a depolarization field. In order to enhance the contrast ratio, a novel driving method referred to as quasi-dc driving was proposed. In the quasi-dc driving, the polarity of the applied voltage to liquid crystals inverts at certain intervals of several seconds. Moreover, the applied voltage and the charging time at the time of polarity inversion are increased more than the intended signals. By this method, the 15-in. TFT-LCD using TLAF with high contrast ratio (more than 100:1) and wide viewing angle was realized.

Application of FLC/AFLC materials to active-matrix devices

The market of TFT-LCDs has been enlarged during the last 10 years. Notebook computers have been the main application. For this application, twisted nematic mode has been used and demands for other modes has been limited. However, larger size of LCDs for monitors or TV are expected to be the next most promising market. Drawbacks of the twisted nematic (TN) mode for this market were narrow viewing angle and slow switching speed. The viewing angle dependence was overcome by using compensation film or by using new LCD modes, for example in-plane switching mode. The slow response is the last drawback to be overcome to realize excellent moving pictures which will be seriously requested in the near future. Several methods have been proposed for fast response of LCDs. However, the applications of ferroelectric liquid crystalline or antiferroelectric liquid crystalline (AFLC) (FLC) materials to TFT-LCDs should be the most promising one. In this article, the authors will review the application of FLC/AFLC materials to TFT-LCDs, such as deformed helix ferroelectric (DHF) mode, twisted FLC mode, monostable FLC mode, APD mode and the application of frustrated phase. Next, the problems to be solved for the application of these materials to TFT devices will be discussed. Finally, the authors will demonstrate the 15″ XGA TFT-LCD using liquid crystalline material showing frustoelectric LC state, which is driven by newly developed driving technologies. Copyright

Electro-optical properties of thresholdless antiferroelectric liquid crystal and its application to high-resolution TFT-LCD

Abstract Thresholdless antiferroelectric liquid crystal (TLAF) characterized by V-shaped switching in a smectic liquid crystal is very attractive for active matrix driving, but the switching mechanism is not fully understood. We have studied electro-optical properties of the TLAF material MLC-0071, and developed a 15-inch TFT-LCD with XGA resolution using the material. Temperature-dependence of relative permittivity suggested the presence of a Goldstone mode. This result implies the V-shaped switching of MLC-0071 is based on a smectic C*-like phase. From the measurements of optical anisotropy etc., it was found that the TLAF had a chevron structure and the molecules oriented parallel to the substrate plane when gray-level voltage was applied. The 15-inch TLAF-TFT-LCD provided wide viewing angle, high contrast ratio and small color shift.