A novel extraction method of the characteristic points for automatic tracking of human motion is proposed. The characteristic points are the points that represent the position and attitude of a human in each frame and can be employed to track the human motion. The extraction is performed in two steps as follows. First, the variance of color image data around each pixel of the human figure is calculated and the pixels that exceed a threshold variance value are extracted as candidate characteristic points. Second, the points are distributed throughout the human figure by prohibiting the existence of characteristic points in certain areas around the determined characteristic points. The proposed method has the advantage that the density of characteristic points can be controlled by adjusting the prohibited area. Human motion is confirmed to be traced using these characteristic points. Each characteristic point is extended to form a square block in order to calculate the degree of matching for the various position of the human figure in the following frames. These characteristic points can trace the human motion using only a few points.

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A twisting ball display system is a promising candidate for Electronic Paper. Dielectric balls with colored hemispheres (black and white) are used as the display elements; each hemisphere has a different surface charge. Each ball can be rotated by applying appropriate electric fields. The rotation behavior of balls is regarded as a result of electrophoretic migration of each hemisphere. We have developed a new method of producing ball elements and checked rotation behaviors of the balls. Two liquid materials with different migration characteristics were gathered in an air and dropped into another liquid, resulting a two-tone colored ball. Rotation behaviors observed at these balls were as estimated as that they depended on the mobility difference between two hemispheres.

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We have developed new materials to achieve a bistable reflective display that can satisfy the requirements of a wide range of viewing angle and high-response, simultaneously, and that has a paper-white appearance. The materials are in powder from showing the liquid behavior. We call the display “Quik-Response Liquid Powder Display (QR-LPD^®:)”. Display units are extremely simple. They consist merely of two substrates, rib and an intervening layer of electric powder. In addition, our display is suitable for plastic type because this display can be driven by PM addressing. So, we can present an ultra-thin and flexible paper-like display. Its thickness is 290μm, which is one of the thinnest reflective displays in the world to our knowledge.

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Electrophoretic displays (EPD) are attracting considerable attentions as a paper-like reflective display. In this paper, we describe a new simulation model for EPD. In the calculation of the kinetics of the pigment particles, we compute the electrohydrodynamics which causes complex flow field due to the electroosmosis. The obtained particle trajectory is analyzed to generate the time variation of the reflectance by using the Kubelka-Munk theory. The simulation results for the cluster formation of the particles on the electrodes and for the overshooting of the reflectance under a constant voltage are shown.

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In Mobile Fine Particle Display (MFPD), fine particles are doped and dispersed within anisotropic liquid (nematic liquid crystals) and the display changes because of the horizontal movement of the fine particles. The fine particles are moved by the synergistic effect of the flow of liquid crystal and the electrophoresis of the fine particles. The MFPD shows excellent paper-like-display characteristics such as a high reflective ratio (approximately 50%), a high contrast ratio (more than 15), and a wide viewing angle. In addition, MFPD can rewrite when electric field is applied and sustain displayed information without electric field for a long time (over several months). These performances of the MFPD indicate that this new-type display is rather suitable for electric paper displays.

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Electrochromic materials, which show reversible color change by electronic stimuli, have been attracting significant interest for potential uses in a paper-like electronic imaging device. Many researches have been extensively focused on viologen or conductive polymers such as PEDOT, as typical organic electrochromic materials. However, they are relatively restricted in the color electrochemically induced. Electrochemical materials showing color changes from clear to the three primary colors such as RGB or CMY should be required to realize full-color electronic paper. In this review, we mainly described electrochromic characteristics of phthalate derivatives from the view point of its color for full-color electronic paper. Advanced technical topics on electrochromic displays are also mentioned.

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Paper-like readability should be positioned as the most urgent target for Electronic Paper, when we consider the present absence of an electronic medium that provides comfortable reading. It is not clear how we should pursue readability; it remains open question as to why we do not like to read books on computer screens. We have recently focused on this theme and are now trying to determine how to achieve readability from our experiments. Our experimental results have shown that there is a large difference of the measured fatigue levels on the two media, display and paper, while there is only a small difference in terms of the measured efficiency. Another experiment has shown that we have a tendency to hurry up and finish incompletely at proofing task on a display. Our measurements of eye mark tracking during reading task have shown that our eyes tend to be too much fixed on a display, and that it can be considered as one of reasons of our eye fatigue at display tasks. Subjective evaluations for favorite reading style have shown that they prefer handheld style than medium fixed style at our reading test on current electronic book terminals.

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