Search

We propose a flicker-reduced time-division light ray quadruplexing technology to improve both the spatial and angular resolutions of three-dimensional (3D) images. The proposed method uses an image-shift optical device with polarization gratings. By optimizing the design of the image-shift optical device and incorporating it into the display system, we confirmed that the resolution characteristics of 3D images displayed at a depth of 30 mm or more can be improved by up to 1.58 times. Furthermore, by developing the display system using a 120 Hz 8K projector with wobbling device and a wavelength-selective λ/2 plate for reducing flicker, we achieved high-resolution 3D image display with deeper depth.

In this study, we investigate three-dimensional (3D) video technology based on spatial imaging to implement a next-generation broadcasting service. This technology allows viewers to watch 3D videos without the need for specialized glasses. However, the main challenge associated with the application of this technology is the large amount of ray information that needs to be acquired and reproduced to improve the quality of the 3D videos. Therefore, we are in the process of actively developing methods to acquire high-density ray information from multiviewpoint images, captured using a multicamera system; in addition, we are devising 3D display methods using multiple display devices. In this paper, we present the most recent results of our research regarding 3D television technologies, including a prototype system based on our novel display method called “Aktina Vision.” This system can reproduce 3D videos of real objects at a resolution of approximately 330,000 pixels, three times that of conventional full-parallax spatial imaging methods using a lens array.

The integral three-dimensional (3D) display is an ideal visual 3D user interface. It is a display method that fulfills many of the physiological factors of human vision. However, in integral 3D displays for mobile applications that use direct-view flat panels to display elemental images, color moire is a problem that occurs because of the sampling of subpixels by elemental lenses and the insufficient resolution and depth reproduction of the reconstructed 3D image. In the conventional moire reduction method, the degree of defocus of elemental lenses has to be set to a large value, which is one of the factors that reduces the performance in terms of depth reproduction. In contrast, only one-step optics can be installed and the installation positions are limited in the conventional wobbling method. This is because, in the method, which uses a birefringent optical element, two-step optics are thicker than the focal length of the lens array. For this reason, it was difficult to achieve ideal moire reduction and depth reproduction performance improvements. To solve these problems, we propose a method that utilizes multiple optical wobbling spatiotemporal multiplexing using polarization diffractive elements and liquid-crystal polarization controllers. Using the proposed method, the wobbling optics can be designed to be thin, allowing two-step optics to be installed between the display panel and lens array. When the moire modulation degree without wobbling is normalized as 100%, it decreases to 25% with wobbling. The proposed method not only achieves effective color moire reduction without deteriorating the 3D image quality, but also can double the resolution of the elemental images to improve the depth reproduction.

Light field displays technologies are popular glasses-free three-dimensional (3D) display methods, whereby natural 3D images can be viewed by precisely reproducing light rays from the objects. However, sufficient display performances cannot be obtained with conventional display techniques because reproduction of a great number of high-density light rays is required for high quality 3D images. Therefore, we develop a novel light field display method named Aktina Vision, which consists of a special 3D screen with isotropic narrow diffusion characteristics and a display optical system for projecting high-density light rays. In this method, multi-view images with horizontal and vertical parallaxes are projected onto the 3D screen at various angles in a superposed manner. The 3D screen has narrow diffusion angle and top-hat diffusion characteristics for optimal widening of the light rays according to the discrete intervals between the rays. 3D images with high resolution and depth-reproducibility can be displayed by suppressing crosstalk between light rays and reproducing them with continuous luminance distribution. We prototype a display system using 14 exclusively designed 4K projectors and develop a light field calibration technique. The reproduction of 3D images with a resolution of approximately 330,000 pixels, which is three times higher than that of conventional display methods using a lens array, and viewing angles of 35.1° in the horizontal direction and 4.7° in the vertical direction is realized by projecting 350 multiview images in a superposed manner.

The integral three-dimensional (3D) display is an ideal visual 3D user interface. It is a display method that fulfills many of the physiological factors of human vision. However, in integral 3D displays for mobile applications that use a direct viewing flat panel to display elemental images, the occurrence of color moire is a problem owing to the sampling of subpixels by the elemental lenses and the insufficient resolution and depth reproduction performance of the reconstructed 3D image. We propose a method to solve these problems that utilizes optical wobbling spatiotemporal multiplexing using a birefringent element and a polarization controller. With the conventional moire reduction method, the degree of defocus of el-ementallenses has to be set to a large value, which has also been a factor that reduces the depth reproduction performance. We show that effective color moire reduction can be achieved with a slight defocus of elemental lenses and without deteriorating depth reproducibility by using the proposed optical wobbling method.

We propose an integral 3D display system that enhances the viewing zone and depth range of reconstructed 3D images using eye-tracking technology and a lens array with a long focal length. To reduce crosstalk due to flipped images caused by the movement of the viewer, a lens arrangement that forms a horizontally widened optical viewing zone by rotating the lens array is designed. Unlike the conventional design, the viewing angle expanded 2.9 times to 81.4° horizontally and 1.7 times to 47.6° vertically, and the depth range doubled. Results of the evaluation experiment confirmed that crosstalk was sufficiently suppressed.

This paper presents an integral three-dimensional (3D) display that efficiently enhances both the pixel densities and viewing angles of 3D images with parallel projection of elemental images. In the proposed method, ultra-high-definition (UHD) elemental images are projected and superimposed as parallel light rays from densely arranged compact UHD projectors onto a lens array. Three-dimensional images with enhanced pixel densities and viewing angles can be displayed by optimizing the projector positions and system design. The prototype yielded a horizontal pixel density of 63.5 ppi, approximately 97,000 pixels, and a viewing angle of approximately 30°, making it superior to previous integral 3D display systems.

Effective compression technology is required to reduce the huge amount of information for integral three-dimensional (3D) television. For compressing an integral 3D image, we propose a compression method of converting elemental images to multiview images and of applying multiview video coding to part of the multiview images and their depth maps. In this method, the relationship between the number of the part of the multiview images and the image quality degradation of a reconstructed 3D image was studied by subjective evaluation experiment, and we confirmed the amount of information required for displaying an acceptable reconstructed 3D image. As a result, the reconstructed 3D images with acceptable image quality were obtained with about 2/9 times the amount of information for coding all the multiview images converted from the elemental images.

We studied an integral three-dimensional (3D) TV based on integral photography to develop a new form of broadcasting that provides a strong sense of presence. The integral 3D TV can display natural 3D images that have motion parallax in the horizontal and vertical directions. However, a large number of pixels are required to obtain superior 3D images. To improve image quality, we applied ultra-high-definition video technologies to an integral 3D TV system. Furthermore, we are developing several methods for combining multiple cameras and display devices to improve the quality of integral 3D images.

Light field displays can provide a naturally viewable three-dimensional (3D) image without the need for using special glasses. However, improving in the resolution of 3D images is difficult because considerable image information is required. Therefore, we propose two new light field display methods that use multiple ultra-high definition projectors to realize a reproduction of a high-resolution spatial image. One of the two proposed methods is based on integral imaging. Multi-elemental images are superimposed onto a lens array using multiple projectors placed at optimal positions. An integral 3D image with enhanced resolution and viewing angle can be reproduced by projecting each elemental image as collimated light rays at different predetermined angles. We prototyped a display system having six projector units and realized a resolution of approximately 100,000 pixels and viewing angle of approximately 30°. The other proposed method aiming at further resolution enhancement is based on multi-view projection. By constructing a new display optical system to reproduce a full parallax light field and by developing a special 3D screen with isotropic narrow diffusion characteristics of non-Gaussian shape, optical 3D images could be reconstructed, which was difficult with conventional methods. We prototyped a display system comprising two projector units and realized higher resolution of approximately 330,000 pixels as compared to our previous full parallax light field display systems.

We present a method to display an integral three-dimensional (3D) image without gaps between multiple display active areas by using multiple liquid crystal display (LCD) panels and multi-image combining optical systems (MICOS). We designed a MICOS to improve the resolution characteristics and decrease the luminance unevenness corresponding to the viewpoint. Furthermore, we developed a method for correcting the distortion of the integral 3D image by using image processing. We prototyped an integral 3D display using four 8K dual-green (8KDG) LCD panels and the improved MICOSs. The prototype display achieved to magnify the display area about 5.66 times more than when a single LCD panel was used.

In the case of using a flat-panel display for displaying elemental images in an integral three-dimensional (3D) display, the color moire on the 3D image caused by the sub-pixel structure for colorization becomes a visual obstacle. Generally, a method of displaying an elemental image through a diffusion screen, or a defocusing method of the elemental image from the focal length position of the elemental lens have been used for color moire reduction. However, on the other hand, this lowers the resolution of the elemental image, which is one of the causes of lowering the depth reproducibility of the 3D image. We developed a technology to reduce color moire, while improving the resolution of reconstructed 3D images by multiple 3D display systems.

We have developed integral three-dimensional (3D) television using an ultra high definition imaging system. The system uses a device having 7680 pixels in the horizontal direction and 4320 pixels in the vertical direction for each of the red, green, and blue channels. A lens array comprising 400 lenses is configured in the horizontal direction and one comprising 250 lenses is configured in the vertical direction. The system is designed to ensure a maximum spatial frequency of 11.3 cycles/degree and a viewing angle of 24 degrees when the display is observed from three times the display height. The setup described here has simultaneously maintained the balance between the maximum spatial frequency and the viewing angle by shortening the focal length of the elemental lens while narrowing the pitch of the elemental lens. We have confirmed the generation of 3D images with an appearance that varies in a natural manner according to the position of the observer.

We studied highly realistic communication systems using a super multiview three-dimensional (3-D) video system. We propose the developed glasses-free 200-in. 3-D display using ∼200 high-definition (HD) projector units to reconstruct natural life-size 3-D moving objects, such as cars and humans. We also analyzed the optimal arrangement of the multiview camera system for the 3-D display. In the experiments, we developed a prototype super multiview 3-D camera system using compact HD video cameras with real-time convergence compensation circuits that correct the captured images via image processing optimized for the display. We also performed demonstration experiments using the developed 3-D display and camera system in a public area. As a result, we highlight several possibilities for actual applications of the glasses-free super multiview 3-D video system.

This paper presents a novel regularity evaluation of placement structure and techniques for handling conditional design rules along with dynamic diffusion sharing and well island generation, which are developed based on Sequence-Pair. The regular structures such as topological rows, arrays and repetitive structures are characterized by the way of forming sub-sequences of a sequence-pair. A placement objective is formulated balancing the regularity and the area efficiency. Furthermore, diffusion sharing and well island can be also identified looking into forming of a sequence-pair. In experiments, we applied our regularity-oriented placement mixed with the constraint-driven technique to real analog designs, and attained the results comparable to manual designs even when imposing symmetry constraints. Besides, the results also revealed the regularity serves to increase row-structures applicable to the diffusion sharing for area saving and wire-length reduction.

We have been conducting research with the objective of achieving three-dimensional (3D) television using integral photography. Extremely high-resolution (EHR) elemental images are necessary to enhance integral 3D image quality. Presently, projection display systems are practical for displaying EHR images and have some advantages for 3D imaging. However, any geometric distortion of the projection lens will cause a positional error between the elemental images and elemental lenses. This positional error subsequently results in a distortion of the reconstructed image and a smaller viewing area. We theoretically and experimentally analyzed the effects of distorted elemental images on a reconstructed image. As a result, a slight distortion of the projection lens, which is proportional to the square of the image height, caused a positional error of the reconstructed 3D image. The depth-direction error of the reconstructed image was larger than that of the lateral direction. Furthermore, the viewing area decreased due to the distortion of the elemental images. From experimental results using a projection-type integral system, we found that image processing for distortion compensation is effective in eliminating distortion and improving the viewing area of the reconstructed 3D image.

We have introduced an extremely high resolution video system 'Super Hi-Vision' at the Kyushu National Museum. This feature opened in October 2005 with the purpose of exhibiting high-quality images of national treasures and traditional arts and crafts to its visitors. The system achieves high resolution using the spatial pixel offset method, quadrupling the horizontal and vertical resolution of HDTV. To display the images with high fidelity, it is important to manipulate the images on the basis of the system characteristics. This paper reports on the efforts to ensure image quality for this Super Hi-Vision System, focusing on resolution and color reproduction.

The morphology of polymer-walls in liquid crystal/monomer mixtures, produced by irradiating selective areas of a cell with non-uniform ultraviolet (UV) light irradiation through a photomask to induce phase separation by photopolymerization, have been investigated using both optical and scanning electron microscopy. It was found that it is possible regulate the morphology of the polymer-walls by controlling the photopolymerization process which occurs during curing in two-phase region. The mechanisms of polymer-wall formation are complex, including local photopolymerization and diffusion processes.

A method is proposed for fabricating extended porous polymer films for spatially aligning liquid crystals. By means of the successive biaxial extension method, polyolefin porous polymer films are extended to a great degree (10µm thick, porosity 72.4%). After the porous polymer films are filled with nematic liquid crystals, a liquid crystal cell is fabricated by attaching glass substrates. The extension factor is 2.4 times and 6 times along the two orthogonal directions. As a result of observation by a polarization microscope, it is recognized that the liquid crystal molecules are aligned along the extension direction within the porous film. An optical modulation function using the birefringence of the liquid crystal is observed on application of a voltage. Unlike the conventional rubbing orientation process, the present scheme does not generate any static electricity or fine dust. Further, high-temperature baking of the alignment layer is not necessary. Orientation processing of liquid crystals is possible with the substrate maintained at room temperature. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 1–8, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10164

We have developed a system of compositing three-dimensional (3D) video images based on the depth information of the objects. The system consists of the Axi-Vision Camera that can measure object distance in real time and an arithmetic image processor that can synthesize video images according to the depth information. The paper demonstrates how to three-dimensionally synthesize such a scene as an array of computer-generated characters moving around a standing person in real time. The feasibility of using such a signal processor to create realistic TV programs in a broadcasting station has been studied.

Organic thin-film transistors (OTFTs) which use Ta2O5 as the gate insulators were fabricated on plastic substrates. The gate insulators were synthesized by anodizing the gate electrodes fabricated as stacked structures of aluminum (Al) and tantalum (Ta) at room temperature. The stacked structure suppressed the stress at the interface between the substrate and metal electrodes so that cracks on Ta could be avoided. The organic semiconductor pentacene was used as the active layer on the gate insulator. The OTFTs showed the best performance at an operating voltage of 5 V and a good field-effect mobility of 0.36 cm2/Vs on plastic substrates. The structural order of the pentacene in the film and the temperature dependence of the leakage current in the insulator were also studied to improve the device characteristics.

When making a TV program in a studio, care must be taken that the camera does not shoot beyond the boundary of the studio set. In addition, limitations in cost and space for the set must be taken into account. In a virtual studio, on the other hand, we can solve this cost and space problem. But in turn, actors have to perform in front of a blue background screen, which is not an easy task. To solve these problems associated with real versus virtual studios, we have developed a new type of virtual studio called the Real Space-based Virtual Studio in which a real space image and a virtual one are combined naturally with no boundary seam. One major advantage in using this new virtual-real hybrid system is that the actors can concentrate on their roles. Another is that the camera work can be done without worrying about off-screen areas. In the present study, we constructed an omnidirectional image with ultra-high definition features and combined it with real studio image. We have developed an integration system and have shown that the omnidirectional and real studio images can be synthesized smoothly and naturally.

We proposed a new flexible ferroelectric liquid crystal (FLC) device containing polymer walls and networks between plastic film substrates. The solution of FLC and monomer sandwiched between the substrates was irradiated with ultraviolet (UV) light through a photomask to form the polymer walls. Polymer walls without optical anisotropy were formed from an isotropic-phase solution to prevent light leakage through the polymer walls under crossed polarizers. Subsequently, uniform UV light was irradiated without a photomask on the solution containing the remaining monomer, and then polymer networks were formed on all except the polymer wall areas. The fabricated FLC device enabled grayscale display operation in the areas with the polymer networks. Even when the device was bent or cut, the device maintained spatial uniformity of light modulation because the polymer structures formed by the above two-step UV irradiation method maintained a constant composite film thickness.

We have studied the dependence of the spatial resolution of polymer-dispersed liquid crystal cells with finely patterned transparent electrodes on their electrooptic threshold properties. In a numerical simulation of the electrical potential based on the finite element method, the slit-patterned transparent electrodes induced a nonuniform electric field distribution in the cell and the spatial change of the electric field intensity significantly decreased with increasing spatial resolution of the slit width. It was estimated that spatial resolutions of 50 line pairs (lp)/mm and 100 lp/mm would lead to saturation/threshold voltage ratios of 2 and 1.5, respectively, in the electrooptic property. When uniform and small liquid crystal droplets were formed by controlling photopolymerization-induced phase separation phenomena, the voltage ratio was decreased from 1.73 to 1.5. The measured limiting resolution reached more than 100 lp/mm, when small slit images displayed by a cell driven by the approximate applied voltage were magnified and sensed using a video camera. The experimental results confirmed the validity of the above resolution simulation results.

This paper describes the alignment of ferroelectric liquid crystal (FLC) structures formed between aligned polymer fibres, where the FLC smectic layers are determined by polarising microscopy and X-ray diffraction. The FLC/polymer composite films were formed from a nematic phase FLC/monomer solution using a photopolymerisation-induced phase separation method. It was found that bending of the FLC smectic layers was induced in both the film plane and the cross-sectional plane at the phase transition from smectic A to chiral smectic C of the FLC material. The light transmittance properties of the composite film between crossed polarizers was analysed by light propagation simulation in several optical anisotropic media, based on the evaluated smectic layer model.

We evaluated the electrooptical properties of free-standing films based on ferroelectric liquid crystals stabilized by a rigid aligned polymer network in anticipation of future development of lightweight, large-area flexible film displays. It was shown that the mechanical strength of the film increased at higher concentration of added monomer, while the speed of electrooptical response declined. This could be a result of restricted switching of the liquid crystal molecules due to their interaction with the surface of the solidified polymer. Although the contrast ratio decreased at higher polymer concentrations, when the concentration of the dispersed polymer was high enough to provide free-standing ability, 100:1 or higher contrast ratios were achieved. In addition, the threshold voltage required for liquid crystal molecular switching was spatially changed due to polymer dispersion, resulting in the appearance of a grayscale display function. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(5): 35–42, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1105

We studied the flare appearing in video images when a liquid crystal filter is used in front of a video camera. To clarify the generating mechanism of the flare, the relationship between the concentration of spacer particles dispersed in the liquid crystal and the intensity of light scattered by the filer was examined in detail by using a schlieren optical system with a laser light beam. We found that the light scattering is mainly caused by the spacers and glass substrates, so we evaluated their contribution ratio. From microscopic observation, we determined that the light scattering originated by the spacers includes light scattered by the spacer particles and that resulting from by liquid crystal alignment deformation caused by the spacer surfaces. As the light scattering of the spacers was in proportion to the spacer concentration, it could be considerably reduced by decreasing the spacer density. The flare in video images was reduced by decreasing the light scattering. The liquid crystal filter fabricated by using the flare-reduction method described above was utilized in actual television program.

In order to correct the color deviation due to variation of illumination in film shooting, a liquid-crystal filter with dichroic dyes that can control the color temperature of the transmitted light in real time has been developed. By using Planck's radiation rule and the Lambert–Beer law, the absorption spectra of the dyes are designed. It is found that the color balance can be adjusted continuously between 4450 and 2530 K. The time needed for control is about 80 ms. When a liquid-crystal filter is used for actual television film shooting, it is confirmed that the color balance of the image can be corrected naturally. The present device is useful in location film shooting for television when the color temperature of the image changes drastically under such conditions as the lighting changing from indoor light to solar light. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(10): 40–48, 2001

This paper describes a chemical study of a new free-standing ferroelectric liquid crystal film containing a rigid fiber network polymer formed by photopolymerization-induced phase separation. The liquid crystal and acrylate polymer separated from a homogeneous solution were individually dissolved by different solvents, and examined by high-performance liquid chromatography and gel permeation chromatography, respectively. The liquid crystal component segregated from the solution including 20wt% monomer had a purity of more than 96%, and contained less than 3% of decomposition products and a little remaining monomer, less than 0.3%. The measured molecular weight of the segregated polymer exhibited a broad distribution from 103 to 106 with a mean polymerization degree of about 100, which increased with monomer concentration. Such a free-standing composite film containing a rigid polymer network is applicable to a shock-resistant ferroelectric liquid crystal display panel because the transparent subs...

The morphology of polymer fiber network formed in ferroelectric liquid crystal devices was closely observed by optical and scanning electron microscopes, and the formation mechanism of the polymer was investigated for obtaining a rigid polymer structure supporting substrates. It was found that aligned polymer fibers are formed with fibril aggregation, which is induced by photopolymerization of monofunctional acrylate monomer aligned in parallel with the liquid crystal molecular alignment. As the monomer concentration increases, the polymer fibers are transformed into thicker and harder structures. This self-assembling phenomenon is thought to be induced by the interfacial tension of the liquid-state polymer with comparatively low molecular weight during the polymerization, and the transient unstable polymer morphology that appears in the phase separation process can be fixed by rapid curing of the polymer material.