We carried out degradation analysis of a blue phosphorescent organic light emitting diode by both impedance spectroscopy and transient electroluminescence (EL) spectroscopy. The number of semicircles observed in the Cole-Cole plot of the modulus became three to two after the device was operated for 567 hours. Considering the effective layer thickness of the initial and degraded devices did not change by degradation and combining the analysis of the Bode-plot of the imaginary part of the modulus, the relaxation times of emission layer and hole-blocking with electron transport layers changed to nearly the same value by the increase of the resistance of emission layer. Decay time of transient EL of the initial device was coincident with that of the degraded one. These phenomena suggest that no phosphorescence quenching sites are generated in the degraded device, but the number of the emission sites decrease by degradation.

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We have fabricated the transparent bottom gate and top gate TFTs using new oxide material of Al-Zn-Sn-O (AZTO) as an active layer. The AZTO active layer was deposited by RF magnetron sputtering at room temperature. Our novel TFT showed good TFT performance without post-annealing. The field effect mobility and the sub-threshold swing were improved by the post-annealing, and the mobility increased with SnO₂ content. The AZTO TFT (about 4 mol% AlOx, 66 mol% ZnO, and 30 mol% SnO₂) exhibited a mobility of 10.3cm²/Vs, a turn-on voltage of 0.4V, a sub-threshold swing of 0.6V/dec, and an on/off ratio of 10⁹. Though the bottom gate AZTO TFT showed good electrical performance, the bias stability was relatively poor. The bias stability was significantly improved in the top gate AZTO TFT. We have successfully fabricated the transparent AMOLED panel using the back-plane composed with top gate AZTO TFT array.

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To explain the variation of the address discharge during an address period, the wall voltage variation during an address period was investigated as a function of the address-on-time by using the V_t closed curves. It was observed that the wall voltage between the scan and address electrodes was decreased with an increase in the address-on-time. It was also observed that the wall voltage variation during an address period strongly depended on the voltage difference between the scan and address electrodes. Based on this result, the modified driving waveform to raise the level of V_scanw, was proposed to minimize the voltage difference between the scan and address electrodes. However, the modified driving waveform resulted in the increase in the falling time of scan pulse. Finally, the overlapped double scan waveform was proposed to reduce a falling time of scan pulse under the raised voltage level of V_scanw, also.

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A replacement of an expensive MgO protective layer with relatively inexpensive Lanthanum Hexa Boride (LaB₆) has already been proposed. Since LaB₆ is not transparent, unlike MgO, the LaB₆ panel employs a long sustain gap structure. Since the sustain gap is 2.6 times larger than the distance between sustain and address electrodes, different driving methods from those of the conventional PDPs have to be adopted. For the driving technique of the sustain period, an application of delayed auxiliary pulses on A electrode and the overlap sustain pulse drive are proposed. Luminance degradation with higher sustain frequency driving can be compensated by use of a 2step sustain pulse driving. Low reset luminance and low address voltage are achieved with a square-ramp technique for the reset period. TV operation is successfully realized on AC PDP which incorporated the LaB₆ cathodes.

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A precision in thickness recycling modus for a displays' color filter surface using a gear-form cathode in microelectrochemical removal is developed in the study. Through the precise removal processes of optical materials of nanostructure of Indium-Tin-Oxide crystallization, the optoelectronic semiconductor industry can effectively recycle defective products, and reducing production costs.

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The self-organized microwrinkles can serve as a surface alignment layer to align nematic liquid crystals, which is primarily based on the groove mechanism. The azimuthal anchoring energy is discussed and estimated from the groove topography and the actual twist angle in the twisted nematic cell.

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Using frictional force microscopy (FFM), the friction surface characteristics were compared between twisted nematic (TN) mode and vertical alignment (VA) mode alignment films (AFs). The friction asymmetry was detected depending on temperature conditions on TN mode AF, but not on VA mode AF. The difference between two modes was explained by leaning intermolecular repulsion caused by the pre-tilt angle uniformity and the density of side chain. No level difference according to temperature conditions appeared when the pre-tilt angle were measured after liquid crystal (LC) injection.

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We developed a new method for characterizing molecular distribution in very thin liquid crystal layer (5-40nm) evaporated onto rubbed polyimide film used by grazing-incidence X-ray diffraction (GIXD). The diffraction peaks corresponding to intermolecular correlation perpendicular to longitudinal axis of liquid crystal molecule and the clear anisotropic distribution of liquid crystal molecules in a thin layer were successfully observed. We found that in the vicinity of the alignment film, the intermolecular spacing correlation perpendicular to longitudinal axis of the 5CB molecule was expanded by the alignment film, and that the ordering of the 5CB was not so high. As the distance from the alignment film the spacing came close to the intrinsic intermolecular spacing.

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We investigated effect of annealing after rubbing by grazing incidence X-ray diffraction, since annealing process is performed in the actual process of liquid crystal display (LCD) fabrication. It was found that rubbed surface polymers were highly crystallized by annealing at 250°C after rubbing, and that the crystallization of surface polymers by annealing occurred in the aligned polymer region induced by rubbing. Crystallization of surface polymers by annealing increasingly occurred as increasing of rubbing strength. Thus, it is considered that annealing process after rubbing should also play an important role to control liquid crystal alignment in LCD.

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A prototype of a novel mobile viewer system consisting of a mobile phone and a 13.1-inch 4096-color electronic paper display has been developed. The basic concept of the system, the technological study for realizing the concept, and the specifications of the prototype are described. Possible applications of the system are also proposed.

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We propose a 2D display and camera arrangement for video communication systems that supports both spatial information between distant sites and user mobility. The implementation of this arrangement is called the “surrounding back screen method.” The method enables users to freely come from and go into other users' spaces and provides every user with the direct pointing capability, since there is no apparent spatial barrier separating users, unlike the case of conventional video communication systems. In this paper, we introduce two properties (“sharedness” and “exclusiveness”) and three parameters (a distance and two angles) to represent the geometrical relationship between two users. These properties and parameters are used to classify the shared spaces created by a video communication system and to investigate the surrounding back screen method. Furthermore, to demonstrate and explore our surrounding back screen method, we have developed a prototype system, called t-Room. Taking into account practical situations, we studied a practical case where two t-Rooms with different layouts are connected.

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The characteristics of a left-handed traveling-wave transistor, which is formulated as two composite right- and left-handed (CRLH) transmission lines with both passive and active couplings, are discussed for generating unattenuated waves having left-handedness. The design criteria for convective instability are described, together with results of numerical calculations that solve the transmission equation for the device.

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A composite patch array antenna with built-in polarizer has been developed to reduce road clutter noise by 20dB for 76GHz automotive radars. A polarizer is placed in front of Tx and Rx patch arrays within their reactive near-field region to suppress cross-polarized sidelobe radiation from their feeding lines while maintaining a low-profile characteristic with 4mm thickness. Additional metal-lined absorbers within the composite antenna structure, while terminating cross-polarized waves undesirably excited by the patch arrays, also serve as miniature clutter plates to further reduce sidelobes toward the road surface. The resultant composite antenna achieved sidelobe levels of -45dB, a 20dB improvement over standard patch arrays, at elevation angles close to 90°.

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This paper proposes a closed-form formula for the jitter-induced noise spectrum at the output of continuous-time ΔΣ modulators with NRZ feedback waveform. In this approach, the clock jitter effects are modeled as an additive noise in the feedback loop of the modulator. Making use of a conceptual model and following from the linear system theory, the output spectrum is explained versus the spectrum of the additive jitter noise.

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