bluuebunny/crossref_metadata_2025 huggingface dataset:
State‐of‐the art of a‐Si TFT/LCD
Authors: Tsukada Toshihisa
Published: July 2007

The state‐of‐the‐art in active‐matrix liquid‐crystal displays based on amorphous silicon thin‐film transistors is described. This type of display appears to be the most promising flat‐panel display, and its mass production has just started to deliver 10‐inch class displays with 300‐K pixels. These display panels will have larger diagonal sizes and higher resolution than previous ones. the production of panels with more than one million pixels has also started.

The factors controlling the design of these large and high‐resolution panels are the gate‐busline delay and the charging and discharging of the signal voltage on the pixel electrode. Analytical results show the panels larger than 30 inches and with a resolution exceeding 1, 000 lines can be designed. Another factor that affects the size and resolution of the panels is the parasitic capacitance of thin‐film transistor (TFT), which degrades the display quality.

The fabrication process is then discussed along with such technical breakthroughs as stacked‐layer gate insulators and aluminum‐gate TFTs.
Poly‐Si TFT and driver integration technology
Authors: Ohshima Hiroyuki , Matsueda Yojiro
Published: July 2007

Polycrystalline silicon thin‐film transistors (poly‐Si TFTs) are currently used in active‐matrix liquid‐crystal displays (LCDs). Driver integration technology of poly TFTs results in compact, high‐resolution TFT‐LCDs. Various kinds of TFT driver circuits are discussed, and their performances are evaluated in the present paper. the use of a quartz substrate for conventional, high‐tempera‐ture processed poly‐Si TFTs limits their application to small LCDs. Low‐temperature processed poly‐Si TFTs on glass substrates will result in larger‐size LCDs at lower cost.
Design of high‐quality TFD‐LCDS
Authors: Mizobata Eishi , Hirai Yoshihiko , Shimizu Kousaku , Uchida Hiroyuki , Kaneko Setsuo
Published: July 2007

The design of high‐quality thin‐film diode liquidcrystal displays (TFD‐LCDs), which are candidates for low‐cost displays, was studied and 9.3‐inch panels were designed and fabricated. the image quality was then investigated. the TFD structure and area, SiNxdeposition conditions, the thickness of the SiNxfilm, and the driving conditions are the main TFD‐LCD design parameters. the SiNxdeposition conditions and the film thickness had already been optimized and fixed prior to our study. In this study, the TFD area and the bias ratio were first investigated by means of a simulator. This showed that the TFD area and the bias ratio must have optimum values in order to satisfy the response time, contrast ratio, and reliability requirements of high‐quality displays; 9.3‐inch color TFD‐LCDs have been designed and fabricated. the TFD structure is of the bridge type. the TFD area is 64 μm2and the bias ratio is 1:9. the panels use a scan line inverse driving method. the image quality is the same as predicted in the simulation and good enough for high‐quality displays.
Three‐axis balanced driving‐type optical head for high‐density optical disc player
Authors: Matsui Tsutornu , Kitahara Shin‐Ichi , Yamagata Hideto , Hanaki Shin‐Ichi
Published: July 2007

In the optical disc player, there is a necessity to correct the jitter caused by the disc eccentricity and rotation irregularity as well as focusing. For this correction, there are both the electrical correction method using a two‐axis optical head with memory and the mechanical correction method of a three‐axis optical head. If the goal is the simplification of the electrical circuit and the lowering of cost, the latter method is advantageous. However, in the tilting of the conventional field lens, the motion of the lens occurs in the direction of track and jitter and, for those in which the numerical aperture is 0.55 and larger, since good convergence characteristics are not obtained with respect to tilting of the lens, the three‐axis method is hardly realized.

Therefore, the lens holder is held by parallel plate springs of rubber material. Thus, by contriving the electrical circuit driving the lens holder for the center of gravity of the lens holder to coincide with the center of the drive, the rotation of the axis could be controlled and an actuator realizing only translational motion effectively in the direction of the three axes (balanced drive method) was proposed and realized. an optical head based on this method was constructed and, with a high‐density (Hi‐Vision laser diode type) disc, a MUSE signal signal‐to‐noise (SN) ratio above 36 dB could be realized and an excellent image was confirmed.
Picture quality of different pixel arrangements for large‐sized matrix displays
Authors: Hara Zen‐Ichiro , Terazaki Nobuo , Shiramatsu Naoki , Iwata Shuji
Published: July 2007

The image information theory is introduced to the study of pixel arrangement for flat displays which has been based mainly on subjective evaluation tests. the objective is to make a theoretical elucidation of the relations between different pixel arrangements‐particularly pixel arrangements of light‐emissive elements for large‐sized matrix displays‐and picture quality.

First, the factors determining picture quality are identified using a picture model incorporating the sampling of the original picture. As a result, the Nyquist limits are shown to be essential.

Second, the Nyquist limits of different pixel arrangements are evaluated. the areas surrounded by the Nyquist limits are shown to consist of colored and discolored regions. This observation is used to relate the Nyquist limits to visual limits and picture quality.

Third, the picture quality of typical pixel arrangements for large‐sized matrix displays is examined. the quality of still and motion pictures displayed by the RGB‐trio and RGGB‐mosaic arrangements are compared by means of subjective evaluation tests and three‐dimensional spectrum analysis. the comparative analysis gives the following conclusions:

In displaying still pictures, the RGGB‐mosaic arrangement has the effective number of pixels about twice the real number of pixels because of the overlaps of adjacent pixels, but the RGB‐trio does not have this effect.

In displaying motion pictures, the RGGB‐mosaic arrangement provides better picture quality than in the case of still pictures but the RGB‐trio arrangement does not.
Diffraction of electromagnetic waves from a line source by a conducting strip
Authors: Kinoshita Teruhiro
Published: July 2007

This paper considers the problem of scattering of electromagnetic waves by a strip conductor when the source is a line current source or a line magnetic current source. the problem is analyzed as a two‐dimensional boundary value problem when the strip conductor thickness is negligibly thin and the distance from the center of the strip to the source is larger than one‐half its width. the expansion functions of the current are selected to satisfy the edge condition. By means of the spectral domain method, the simultaneous equations for the expansion coefficients and the specific expressions for the coefficients are derived. the current distributions and the scattered far field are computed numerically. In the analysis process, it is shown that the coefficients derived are identical to those of the simultaneous equations in the analysis for the plane wave incidence making use of the Weber‐Schafheitlin discontinuous integral.
Optical imaging characteristics of direct‐contact type linear‐image sensor
Authors: Nagata Tatsuya , Shimizu Hiroya , Watanabe Michihiro
Published: July 2007

An analysis program is developed to evaluate the readout ability of the direct‐contact type linear‐image sensors that do not possess the image‐forming optical systems. It is used exclusively to evaluate the readout characteristics of the direct‐contact type linear‐image sensors. the program deals with the sensors with multi‐layer structures parallel to the XY plane of the 3‐D (and mutually orthogonal) XYZ coordinate system. the optical path of the illuminating light emerging from the source, attenuations at the boundaries between different materials and the lights blocked by the electrode and the receiver are calculated if they are used in determination of the illumination distribution in the XY plane. the calculation procedure comprises two parts: the illumination on the document plane due to emerged light from the source, and the reflected light from the document onto the sensor. This program takes not only document plane reflections into account but can also factor in the reflections caused by light penetrations into the document paper (Yule‐Nielsen effect). Investigations using this program show that the resolution of the read‐out function of direct‐contact type sensors strongly depends on the distance from the document to the receiver and the quality of its paper.
Frequency divider based on miller integral‐type SC astable multivibrator
Authors: Sasaki Hirofumi , Yahara Mitsutoshi , Kawahara Keiji , Zhu Hong‐Bing , Ueno Fumio
Published: July 2007

In a conventional‐type astable multivibrator, the upper limit of the division ratio for stable dividing operations is at most 1/20. In this paper, we propose and analyze a frequency divider based on the Miller integral‐type switched capacitor (SC) astable multivibrator that maintains stable operation even with a large dividing ratio.

This divider has a circuit configuration in which the state reversal occurs at a point during the straight fall of the output voltage waveform of the Miller integrator in a stepwise fashion. Therefore, the divider is not affected by either supply voltage or external noise. the dividing ratio can be varied in a much larger range than that of the conventional type simply by changing the value of the capacitor. the mathematical formula can be expressed simply with only circuit parameters. the computed values and the measured values agree well.

Also, since no trigger generator is needed (as is the case with a conventional type), the dividers can be cascaded easily. the resultant dividing ratio is the product of the individual dividing ratios. Further, by using two sets of modifications of this divider and by using one of them as the feedback circuit, a pulse number converter can be realized in which the ratio of the input pulse number and the output pulse number can be varied arbitrarily.
Performance of partial response system in perpendicular magnetic recording
Authors: Osawa Hisashi , Okamoto Yoshihiro , Kurihara Yoshitake , Nishida Yasutaka , Muraoka Hiroaki , Nakamura Yoshihisa
Published: July 2007

The error‐rate performance of the partial response maximum likelihood (PRML) system combining the partial response (PR) system with the Viterbi decoding, which is a type of maximum likelihood (ML) decoding, is investigated in perpendicular magnetic recording using a multilayered main‐pole head. Waveform approximation is carried out with regard to the isolated reproducing waveform obtained by experiment; and, based on this, the bit error rate is determined by computer simulation.

First, taking into account the noise increase due to equalization, the signal‐to‐noise ratio (SNR) at the discrimination point and the bit error rates of bit‐by‐bit decoding of several PR systems using the characteristics of the multilayered main‐pole head are determined. Next, the bit error rates of the PRML system are determined for these PR systems and then compared with those for the conventional PR system. Then it is clarified that the best performance is obtained by the PR(1, 0, 0, 0, ‐1) system among these PR systems, and the improvement of SNR compared with the conventional PR system is about 1.9 dB in the case of the bit‐by‐bit decoding system and 4.1 dB in the case of the PRML system at an error rate of 10−4.
Analysis of radiation characteristics of a polyhedron‐approximate reflector antenna using the aperture integration method and the current distribution method
Authors: Hanayama Eiji , Takano Tadashi
Published: July 2007

In this paper, the radiation characteristics and its analysis method are discussed for a polyhedron‐approximated reflector antenna in which the reflector is made of several planar facets as in a large deployable antenna. Based on the current distribution method considering the law of reflection and the effect of diffraction, the aperture integration method using the ray tracing containing an approximation in the law of reflection is used for the electric field distribution of a polyhedron‐approximated antenna. It is found that the electric field of the present antenna becomes maximal at the joint between the facets. It is shown that the far‐field characteristics of the antenna derived by the aperture integration method based on the approximate ray tracing and by the current distribution method are identical. the relationship was found between the equivalent aperture plane where the field distributions derived by the two methods are identical. Further, by means of the rigorous ray tracing method, the three dimensional ray behavior is shown. It is found that the aperture integration method based on the rigorous ray tracing method is inappropriate for the calculation of the radiation characteristics of the present antenna.
Equivalent impedance of building columnc and girders against lightning surges
Authors: Sato Masaji , Kuramoto Shoichi
Published: July 2007

If a telephone center building is subject to a direct hit by lightning, lightning surge currents flow in the columns, girders, and walls and, hence, the equipment may be damaged or may malfunction due to induction into the communication cables and power lines. Studies on the current and voltage distributions in the building by the direct lightning hit have been carried out. One of the fundamental subjects is the method of estimating the equivalent impedance of actual columns and girders. There has been no sufficient understanding because the dimensions of the steel frames are large and the shapes are extremely complex.

In this paper, scaled‐down models of the columns and girders are constructed first and the impedance measurement method for these models is discussed. It is found that the current distributions in the model become almost homogeneous if several return wires are placed around the scaled model of the column so that a measurement close to an actual situation can be carried out.

Next, by means of this measurement method, a simple cylindrical conductor rod and the scale model of the column are compared. Hence, it is proven experimentally that the resistance and the inductance of the columns and the girders can be estimated from the computational equation for the cylindrical conductor rod with identical surface area to those of the steel frame and the steel rod, even if the shapes are complex.

Finally, the actual columns of a reinforced concrete building are measured and agreement is confirmed between the estimate from the scale model and the actually measured values.
Analytical solutions of the scattering properties of h‐plane junctions in rectangular waveguides
Authors: Widarta Anton , Kuwano Shuzo , Kokubun Kinchi
Published: July 2007

The scattering properties of the H‐plane waveguide discontinuities such as the cross junction, T‐junction, and right‐angle bend are analyzed taking their symmetry into account. the solutions are synthesized in two new and simple expressions. These solutions are treated rigorously by the mode‐matching method in which each junction section is divided by a circular region and the electro magnetic fields are matched with the scattered waves into waveguide regions at the boundaries. By means of the accurate numerical results obtained in a wide frequency range, the scattering properties of the H‐plane junctions in a standard waveguide and an oversized waveguide are examined in detail. the latter is believed to be useful for an approximnte estimation of the scattering properties of crossing roads in underground shopping centers.
LiNbO3 optical waveguide modulator for bidirectional transmission
Authors: Ishikawa Tadasu , Furuta Hiroyuki
Published: July 2007

A new bidirectional external optical modulator using Fresnel reflection light has been proposed and developed. Since weak light reflected from the end of a crystal can be modulated in this modulator, no laser source is required if the modulator is intended for home use. This modulator also has no significant effect on a video signal in the downstream. In the external modulator designed for trial use, insertion loss was less than 3 dB, the half‐wave voltage was 10 V, and the half‐wave voltage difference and phase difference between the two modes were 2 percent and 5 degrees. A small module of the present device was created for use in a home optical terminal station of a demand access‐type Hivision CATV system. In this bidirectional transmission experiment, stable channel selection and good Hivision receiving image with C/N > 20 dB were confirmed. For the uplink 64 kbit/s NRZ signal, bit error rate (BER) of less than 10−8 was obtained.
Precise formula for calculating spot size in optical waveguides and its accuracy
Authors: Kokubun Yasuo , Tamura Shuichi
Published: July 2007

Spot size is a fundamental parameter that expresses the degree of spreading of the transverse electric field distribution of a guided mode. This quantity is used when there is offset loss between different guided wave elements. It is extremely important to determine an accurate spot size value in the design of an optical integrated circuit containing a number of guided wave devices. the goal to derive a highly precise spot size requires a least square approximation of a transverse electric field distribution of the guided wave in terms of the electric field of a Gaussian beam.

The transverse electric field distribution of the fundamental mode propagating in an optical waveguide was expanded orthogonally in terms of Hermite‐Gaussian functions. With a 0th‐order expansion coefficient as the maximum, an approximate equation suitable for highly accurate numerical computation was derived. the present equation does not change its equation form by Fourier transform and has mathematical validity. Fur ther, when the approximate equation is used in the present study, the junction loss of the offset axes of the waveguides can be approximated best by that of the Gaussian beam waves.

This paper uses as an example the TE mode in a three‐layered slab waveguide in studies of approximation accuracy for the defined spot size value. With the present approximate equation, the spot size can be derived accurately by a successive approximation. It was demonstrated with an actual successive approximation that accuracy improves significantly and is better than the one obtained from a conventional equation.
Quantum energy control of multiple‐quantum‐well structures by selective area mocvd and its application to photonic integrated devices
Authors: Aoki Masahiro , Suzuki Makoto , Sano Hirohisa , Taniwatari Tsuyoshi , Tsutsui Takayuki , Kawano Toshihiro
Published: July 2007

Quantum energy control is proposed in the form of a multiple‐quantum‐well (MQW) structure fabricated by selective metal organic chemical vapor deposition (MOCVD) growth to obtain high‐performance multiple‐function semiconductor photonic integrated devices. Its fundamental principle and the applied photonic integrated device are discussed. In general, semiconductor photonic integrated devices require semiconductor layers with different bandgap‐energy states for each structural device having a different function formed on the same semiconductor substrate.

In this paper, the position‐dependent growth speed and the growth‐layer compositions on the substrate are controlled by selective MOCVD growth so that the quantum energy levels of the InGaAs/InP MQW structures grown simultaneously are varied over the substrate surface. As a result, a controllable range of the quantum energy level spanning over 200 meV and a high‐quality crystal configuration of selectively grown layers comparable to that formed by conventional growth processes have been confirmed.

Application of this new integration method required that we design a monolithic integrated device of a distributed feedback laser diode and an electric field absorption‐type modulator, as well as a multiple‐wavelength distributed feedback laser array. Despite the simple design method, good crystal quality of the selectively grown layers, good optical coupling between the devices, and good device performance were observed.
Surface operating optoelectronic devices and applications to optical parallel processing
Authors: Hara Kunihiko , Ohta Jun , Nitta Yoshikazu , Kyuma Kazuo
Published: July 2007

Since, in surface operating semiconductor optoelectronic devices, signal reception and transmission are carried out in the direction perpendicular to the device surface, numerous parallel processes can be achieved using two‐dimensional arrays of these devices.

To realize image processing systems, massively parallel computing systems and high‐speed/high‐capacity communication systems, there has been considerable research on surface operating optoelectronic devices.

This paper describes the operating principles and present status of typical surface operating optoelectronic devices and discusses the electrical and optical connections in a three‐dimensional (3‐D) parallel optoelectronic system using two‐dimensional operating optoelectronic device arrays. Finally, applications to optical switching networks, direct image processes and optical neural networks will be introduced.
Hybrid optical integration technology
Authors: Kobayashi Morio , Kato Kuniharu
Published: July 2007

The combination of hybrid integration technology with guided‐wave optical technology is expected to provide more functional optical devices with high performance, compactness, and high productivity.

This paper reviews recent developments in the hybrid integration of optical and electronic components with a silica‐based planar lightwave circuit on silicon. First, edge‐hybrid, surface‐hybrid, and film‐hybrid integration technologies are described. Next, basic technical issues concerning optical component integration, electronic component integration, and packaging are discussed. Emphasis is placed on optical alignment, component fixing, mode‐field matching, and antireflection techniques in the optical component integration. Finally, examples of fabricated hybrid‐integrated optical devices are presented.
Improvement of reconstructed images with binary digital phase holograms using error diffusion methods
Authors: Tanaka Ken‐Ichi , Shimomura Teruo
Published: July 2007

Some error diffusion methods have been reported which are applied to amplitude quantize holograms, kinoforms, and trinary digital phase holograms. However, there is no method which is applied to binary digital phase holograms.

This paper discusses improving reconstructed images with binary digital holograms using error diffusion methods in computer simulation. Consequently, it is clarified that error diffusion methods are effective, in general, in the range of reconstructed images not in contact with the diffused noise and the maximum ratio of an input domain is approximately 1:8.

In the range of reconstructed image that does not contact with diffused noise, the error diffusion method gives a superior reconstructed image compared with any other encoding methods. Further, reconstructed images by computer simulation are verified and the deterioration factor in optical systems using optical experiments is eliminated.
Planar lightwave circuits based on silica waveguides on silicon
Authors: Suzuki Senichi , Kawachi Masao
Published: July 2007

Optical communication systems are expanding from the conventional point‐to‐point system to the mesh‐type network systems for subscribers. As a result, the requirement for passive circuits such as optical divider, optical combiner, and optical switch is increased. Since optical waveguide‐type circuits have superior stability and mass producibility, they are considered important for construction of future optical communication systems.

This paper describes development of the planar lightwave circuit (PLC) technology using the silica‐based waveguide on a silicon substrate. In the first half, the design technology of the silica‐based waveguide, the design and production examples of PLCs, and the system experiment examples are introduced. In the latter half, the latest tendency of high‐density integrated PLCs is emphasized based on the use of the high relative refractive index difference (high‐Δ) with a view to large‐scale PLC, and the characteristics of the high‐Δ waveguide and examples of its applications to high‐density integrated optical circuits are presented.
Er‐doped silica‐based planar ring resonator
Authors: Hattori Kuninori , Kitagawa Takeshi , Oguma Manabu , Hibino Yoshinori , Ohmori Yasuji , Horiguchi Masaharu
Published: July 2007

A new configuration of a ring resonator is proposed by using an Er‐doped silica‐based waveguide. Its laser oscillation and variable finesse were realized. to determine the Er concentration suitable for the Er‐doped waveguide ring resonator, the Er concentration dependence of the threshold pump power for laser oscillation in an Er‐doped waveguide ring resonator is analyzed numerically. It was found that an optimum Er concentration is in the range of 0.3 fc 0.5 wt.%. Further, from the actual measurement, it is confirmed that the gain of the silica‐based waveguide with Er doping concentration in this range is larger than the loss of the ring resonator. Then, an optimum coupling condition of the directional coupler is studied. It is found that a maximum value of 91 percent is obtained as the coupling ratio at a wavelength of 1.533 μm for a coupling length of 1.0 mm. Based on these investigations, an Er‐doped waveguide ring resonator with a circumferential length of 9.2 cm is fabricated. As a result, an Er‐doped waveguide ring laser is realized that has an oscillation center wavelength of 1.533 μm, a threshold value of 93 mW for the pump power and a slope efficiency of 0.3 percent. the oscillation modes of the realized ring laser are longitudinal multimodes with its free spectral range (FSR) of 2.2 GHz. the narrow line characteristics of an average line width of 200 kHz are found. From the results of the transmission spectral measurement, it is confirmed that the Er‐doped waveguide ring resonator works as a stopband‐type optical frequency filter. In addition, it is found that the finesse can be varied by controlling the pump power. Maximum finesse is 36.
Frequency dispersion and modulated signal distortion characteristics of gaas power MESFETs at large signal operation
Authors: Miyatsuji Kazuo , Furukawa Hidetoshi , Ueda Daisuke
Published: July 2007

In the search for a cause of modulated signal distortion of a GaAs power FET, an analysis is made for the frequency dispersion caused by the surface trap. First, the frequency dispersion characteristics of the Vgs‐Id relationship of the FET under a large signal operation are measured. It is found that the Vgs‐Id characteristics at high frequencies are very different from the one at dc. It is found that the drain current decreases near Vgs = 0 V. Further, simulation is carried out for the intermodulation distortion using the Vgs‐Id characteristics at the high‐frequency region. It is found that an increase in the nonlinearity of the Vgs‐Id characteristic due to frequency dispersion is the cause of increased modulated signal distortion. From the measured temperature dependence of the frequency dispersion of the drain current, energy levels related to the dispersion are found to be 0.56 and 0.19 eV. Further, a comparison is made between SiN and SiO2 surface passivation films. It is found that frequency dispersion is small and a low distortion characteristic can be obtained with the SiN film.
Generation mechanism of intermodulation products in a traveling wave tube
Authors: Hirata Hitoshi , Kanai Hisashi
Published: July 2007

To study methods for improvement of the intermodulation product of a traveling‐wave tube which amplifies multiple frequencies, the general mechanism was investigated by a large signal analysis. the origin of the intermodulation product is in the nonlinearity of the traveling‐wave tube. Previously, the phase nonlinearity has been considered important from the discussion of polynomial expansion of the amplitude and phase transfer functions.

In this paper, the relationship between the intermodulation product and the phase nonlinearity is reevaluated theoretically and experimentally for various conditions. At the same time, the modulation components of the electron beam charge density are studied as a factor related directly to the generation of the intermodulation product. As a result, it was found that the fundamental component of the charge modulation components which is in phase with the circuit wave voltage best represents the tendency of the third‐order intermodulation product.
High‐speed (20 Gb/s), low‐drive voltage (2 Vp‐p) strained InGaAsP mqw modulator/DFB laser light source
Authors: Kotaka Isamu , Sato Kenji , Wakita Koichi , Yamamoto Mitsuo , Kataoka Tomoyoshi
Published: July 2007

This paper describes a monolithically integrated light source module of a high‐speed/low‐driving voltage multiquantum well (MQW) optical modulator and DFB laser for 1.55‐μm applications. This paper investigates: (1) device structure suitable for growing high‐quality crystal, (2) efficient performance due to adoption of a strained InGaAsP MQW, (3) reduction of device capacitance using polyimide at the electrodes of the optical modulator, and (4) realization of a monolithically integrated module using lens coupling.

In the test device, the oscillation threshold current was below 15 mA, the extinction ratio was over 20 dB when the bias voltage was −2 V, the frequency band was 15 GHz (−3 dB), and the optical power coupled to an optical fiber was 2.5 mW. Optical modulation at 15 Gb/s was carried out at a driving voltage of 1 Vp‐p. When this device was used under 2 Gb/s high‐speed modulation using a driving voltage of 2 Vp‐p for 100‐km transmission, the minimum optical power sensitivity was −23 dBm and the power penalty was 1 dB. This result indicates that this monolithically integrated optical source is suitable for large‐capacity/long‐distance optical communication.
An analysis of striplines with trapezoidal conductor cross sections
Authors: Hasegawa Tsuyoshi , Atsuki Kazuhiko , Li Keren , Yamashita Eikichi
Published: July 2007

As monolithic integration of the microwave circuits progresses, the microstrip line used as a fundamental transmission medium becomes extremely small in size. As the transmission line is miniaturized, it becomes necessary to consider the effect of the shape of the edges of the strip conductor in addition to the thickness. In this paper, an integral equation is derived for the charge density distribution on the strip conductor surface as the unknown. The transmission line characteristics are obtained by discretizing the integration range. Further, the effect of the trapezoidal cross section of the strip conductor formed by etching and plating on the characteristic parameters is specifically studied.
Finite‐element analysis of three‐dimensional chirowaveguides using hybrid edge/nodal elements
Authors: Maruyama Shinji , Koshiba Masanori
Published: July 2007

A numerical approach based on the vector finite‐element method using hybrid edge/nodal elements and full components of electric or magnetic field is proposed for analysis of three‐dimensional chirowaveguides. Chiral‐loaded circular waveguides and buried circular chirowaveguides are analyzed using the present method, and then the validity and usefulness of the method are discussed based on the detailed numerical accuracy analysis.
Investigations on multicolor display by organic luminescent devices with optical microcavity structure
Authors: Nakayama Takahiro , Kakuta Atsushi , Nagae Yoshiharu
Published: July 2007

The emitted light of an organic electroluminescent (EL) device has a narrow half‐width in its spectrum and its intensity is high if a semitransparent mirror is placed on the light‐emitting side and the optical distance between the mirror and a metal electrode is set on the order of the emitting wavelength. This phenomenon is believed to be due to microcavity formation. This paper shows that device characteristics can be explained qualitatively by equations derived from the propagations. It is also shown that it is possible to obtain different colors from the same device material using this characteristic. The basic device structure for multicolor display will be shown. The dependence of luminescence on the detecting angle is theoretically and experimentally confirmed, and it is concluded that the device can be used for display applications.
Degradation mechanism of impregnated cathodes
Authors: Mita Nagahisa , Shimokawa Kiyoshi
Published: July 2007

To better understand the degradation mechanism of impregnated cathodes, chemical compositions of impregnated cathodes after extended usage were analyzed using a newly devised integral method. The results indicate that cathode degradation is caused by a decrease in Ba supply rate. This decrease is caused by an inward drift of the reaction front as the reaction between an impregnant and a tungsten substrate proceeds. It is also confirmed that the Ba supply rate is controlled by the Knudsen flow of Ba atoms.

To compare cathode lives economically, a new diode tube has been designed with an anode that has a taper hole. The diode tube allowed economical measurement of cathode performance (which is almost identical to that of a traveling wave tube (TWT)). The testing of diode tubes confirms that it is possible to estimate the lives of the cathodes with various compositions by the method based on ΔT90. The methodology has been applied to identify the cathode with the longest life from four impregnated cathodes employed in satellite applications.
Computer‐generated holograms by error‐diffusion method using peano curve
Authors: Tanaka Ken'Ichi , Shimomura Teruo
Published: July 2007

Several investigations on error‐diffusion methods using raster scan for computer‐generated holograms have been described in the literature. However, very little is known about the influence of the procedure applying the Peano curve to computer‐generated holograms. This is because the Peano curve has become effective in recent years in connection with related fields of application.

In this paper, the error‐diffusion method using the Peano curve is discussed in detail for the improvement of reconstructed images with computer‐generated holograms. It is clarified under the limitation of area of noise and brightness of images that the error‐diffusion method using the Peano curve gives superior reconstructed images compared with that using raster scan.
Fast‐fourier transform beam‐propagation method using Fadé approximant operators
Authors: Yamauchi Junji , Shibayama Jun , Nakano Hisamatsu
Published: July 2007

The (1, 1) Fadé approximant operator is applied to the fast Fourier transform beam‐propagation method (FFT‐BPM). The Fadé operator for FFT‐BPM is derived, and its relation to the wide‐angle and paraxial operators is investigated. Next, the propagation error of the fundamental mode of a straight step‐index waveguide is evaluated by the mode mismatch loss. It is proved that, in contrast to the wide‐angle operator, Fadé operator does cot exhibit loss, even at small transverse grid‐widths. Finally, as an example of when transverse propagating waves cannot be neglected, the problem of fundamental mode propagation in a tilt waveguide is investigated. It is clarified that the Paé operator preserves an accuracy comparable to that of the wide‐angle operator, even if the tilt angle is widened up to 25 degrees.
A design and fabrication of millimeter‐wave microstrip antenna with monolithic microwave integrated circuits
Authors: Ohmine Hiroyuki , Matsunaga Makoto
Published: July 2007

This paper describes a design method in the millimeter‐wave frequency region for an aperture‐coupled microstrip antenna which unifies a feed network consisting of a monolithic microwave integrated circuit (MMIC) which affects the antenna characteristics at millimeter‐wave frequencies, the shift of the location of the radiating element which is important in actual configuration in the millimeter‐wave region, and the effect of the adhesives. Based on this design, an antenna was fabricated. A quartz substrate was used for the radiating element, while a GaAs substrate was used for the feed network. A high radiating efficiency of 87.1 percent and a wideband characteristic of 3.1 percent with VSWR < 2 were attained. As an application of this structure, a test fabrication is reported on the aperture coupled microstrip antenna in the 40‐GHz band in which an MMIC frequency converter is integrated.
Millimeter‐wave indoor high‐capacity transmission characteristics
Authors: Nakayama Yuji , Sato Akio , Yoshida Teruaki
Published: July 2007

To realize a high‐capacity wireless access, the millimeter‐wave frequencies have been investigated. Research on indoor multipath propagation has been pursued intensively.

This paper proposes an evaluation method for the millimeter‐wave indoor high‐capacity digital transmission characteristics. First, the broadband propagation characteristics under indoor multipath environment were measured so that the multiple‐wave configurations are clarified.

Next, to quantify the digital transmission characteristics under the multiple wave environment, the level ratio (D/U) of the desired wave to the interference wave was evaluated for a bit error rate of 10−4by means of a 4 PSK‐100 Mb/s and a multipath fading simulator. It was found that the bit error rate is determined by the level ratio (D/UT) of the desired wave to the total interference waves and not by the delay time of the interference wave if the delay time of the interference wave exceeds the symbol duration and that the desiredD/UTapproaches the signal‐to‐noise (S/N) ratio (N: Gaussian noise) giving such a bit error rate. From the foregoing results, this paper proposes a channel design method using theD/Uin indoor high‐capacity wireless communication.
Analysis of optical directional coupler with nonparallel transition sections
Authors: Yasumoto Kiyotoshi , Shimoyama Nobuko , Hirata Tetsuto
Published: July 2007

Two optical waveguides comprising a directional coupler, approach each other gradually through curved waveguide sections from the input ends where the two are sufficiently distanced with negligible coupling. After the coupling section where the two waveguides are placed in parallel, the two are separated again through curved sections to the output ends where they are sufficiently distanced with negligible coupling.

In the treatment taking into account the bends of the waveguides, the optical waves propagating through the two waveguides are approximated for simplicity by a superposition of the even and odd local normal modes. The coupling between the guided modes and the radiation wave at the bends often is neglected.

In this paper, the method proposed by Sawa for the analysis of the coupled mode equation taking into account the coupling between the guided modes and the radiation modes in the waveguide system including the curved sections is used for the analysis of the directional coupler including the curved sections. The coupling length and power transfer rate are computed for the directional coupler with curved sections represented by a linear function, a cosine function, and a hyperbolic tangent function. The numerical results indicate that the radiation loss is the smallest and an excellent power transfer rate can be obtained if the shape of the curved section is a hyperbolic tangent function.
An analysis of periodic waveguides by coupled‐mode theory and finite element method
Authors: Ohkawa Yuichi , Koshiba Masanori , Hirayama Koichi
Published: July 2007

As a simple method for evaluating the reflection and transmission characteristics of a grating waveguide, an analysis procedure is proposed and formulated that is a combination of the coupled‐mode theory and the finite‐element method. The finite‐element method is used for the determination of the coupling coefficients in the coupled‐mode equations. Therefore, the present method is capable of analyzing a grating waveguide with an arbitrary shape. In addition, the energy storage effect of the nonpropagating modes is automatically included. Specifically, an index‐modulation type grating reflector is analyzed so that the validity of the method is confirmed. Also, the present method is applied to the design of a grooved grating reflector so that its usefulness is demonstrated.
Development of a simulation technique for thin‐film transistor liquid‐crystal displays
Authors: Ohta Masuyuki , Tsumura Makoto , Ohwada Junichi , Ohida Jun
Published: July 2007

For active matrix liquid crystal displays (LCDs) using amorphous silicon thin‐film transistors (a‐Si TFTs), a novel simulation technique was developed. This simulation technique makes it possible to analyze accurately the fluctuation in the source voltage of the gate voltage trailing edge (feedthrough voltage) that is the main cause of image quality degradation in the TFT‐LCDs; consequently, we can accurately predict the image quality in the TFT‐LCDs. The following are the two features: (1) a‐Si TFT model considering the intrinsic capacitance which causes the dependence of the feedthrough voltage on the drain voltage is constructed; and (2) an analysis method for the gate voltage waveform distortion to calculate the difference of the feedthrough voltage between pixels depending on each pixel position in the TFT‐LCD has been extended from the analysis using an RC delay circuit to a matrix analysis using TFT matrix network. The feedthrough voltage obtained by this simulation method agrees with the measurement within 10 percent.
Tuning bandwidth enhancement in waveguide optical second‐harmonic generation device using phase‐reversed quasi‐phasematching grating
Authors: Fujimura Masatoshi , Suhara Toshiaki , Nishihara Hiroshi , Bortz M. L. , Fejer M. M.
Published: July 2007

Recently, the conversion efficiency of waveguide quasi‐phasematched second‐harmonic generation (SHG) devices has improved rapidly so that factors other than conversion efficiency now limit the utility of these devices. One practical problem is the narrow wavelength and temperature‐acceptance bandwidths.

This paper demonstrates a technique for enhancement of the bandwidths while maintaining a high SHG efficiency. The experimental results are in excellent agreement with the theoretical calculations. The technique may contribute to the practical utilization of the waveguide quasi‐phasematched frequency conversion devices.
Double‐cylindrical cavity multiple‐device structure for stabilized high‐output power combiners
Authors: Tanaka Satoshi , Nogi Shigeji , Fukui Kiyoshi , Ohshima Hideaki , Ohta Keiichi
Published: July 2007

As a method to overcome the moding problem by injection locking while the number of devices is increased when multiple device power combining is carried out with a cylindrical cavity, a power combiner of a double‐cavity multiple‐device configuration was proposed in which the oversized cavity with the desired mode of TMOnO(n⩾ 2) is connected by a coaxial line to a fundamental mode cavity with the same frequency of the TMOnOMode.

First, by means of the modal analysis using the equivalent circuit model of the oscillator, the condition for sustaining the desired mode, the condition for suppression of the undesired mode, and the condition for existence of the double mode are obtained so that the range of stable growth of each mode is found. It was shown that the suppression of the undesired mode can be accomplished and the stable oscillation of the desired mode becomes easier by the present configuration.

Further, as the oversized cavity, the TM020‐mode octuple‐device cavity and the TM030‐mode 15‐device cavity were used in the power‐combining experiments. The power‐combining efficiency of 91 and 95.8 percent was accomplished. With respect to the growth range of each mode, the theory and the experiment agreed qualitatively.
High‐frequency analysis of electromagnetic scattering due to a dielectric cylinder
Authors: Sasamori Takayuki , Uno Toru , Adachi Saburo
Published: July 2007

As a canonical problem to understand the electromagnetic scattering by a dielectric body, the scattering characteristics of the plane wave by an infinitely long dielectric cylinder is analyzed by a high‐frequency approximation. The rigorous solution of the scattered electromagnetic field by a circular cylinder is separated into the component scattered by the cylinder surface and the one transmitted into the interior of the cylinder by means of Watson transformation and Debye expansion. By applying appropriate high‐frequency approximations to each component, geometrical optics representations for reflection, transmission, and diffraction are provided. Especially for the diffracted field, an approximate solution more accurate than the conventional approximate solution is obtained.

By UTD extended to a dielectric cylinder problem, an approximate solution in the transition region is derived which has not been derived by the conventional high‐frequency approximation. To investigate the validity of these approximate methods, the results of the analysis by the present method are compared numerically with the rigorous solutions in the frequency domain and the time domain. It is proven that the present high‐frequency approximation method is extremely accurate except near the critical scattering angle.
Sticking trouble rate on Cd‐added Ag‐based contacts
Authors: Kubono Takayoshi
Published: July 2007

Because the Ag‐oxide dispersed alloy‐type Ag/CdO electrical contact is supposed to have superior welding resistance, this type of contact has been used for circuit breakers designed for medium current. However, there has been no report made on the comparison between the sticking characteristics of Ag/CdO and Ag/Cd contact members.

Contact members made of Ag, Ag/CdO 12 wt% and Ag/Cd 11 wt% were mounted in relays with a breaking force of 15 gf, and the ratio of sticking problems in each contact member was investigated during make‐and‐break operations of a dc 30V‐3Q resistive circuit. When the breakers were used for the make‐and‐break or break‐only operation, there was almost no sticking problem, regardless of contact material type. However, when the Ag/Cd contacts were used for make‐only operation, the sticking problem occurred in as much as 50 percent of the cases. When the Ag/CdO contacts were used for the make‐only operation, it was as high as 90 percent. When the Ag/Cd and Ag/CdO contact members were used for make‐only operation, a large pip and crater were observed on the surfaces of the electrode pairs.

In addition to the experimental results described here, when the contact sticking occurred, the difference in the contact resistance values before and after the make‐only operation was evaluated. The main cause of the sticking problem was believed to be the locking between the pip and crater on the surfaces of the contact electrodes.
A built‐in self‐test structure for arithmetic execution units of VLSIs
Authors: Ikenaga Takeshi , Takahashi Jun‐Ichi
Published: July 2007

This paper proposes advanced built‐in self‐test (BIST) structures: a bit‐distributed pattern generator (BDPG) and a multistage space compressor (MSSC) for arithmetic execution units of VLSIs. By focusing on the regularity of the arithmetic execution units, the required area overhead of the BIST circuits is less than that of conventional ones. The experimental result shows that these structures can reduce almost 60 percent of the hardware overhead of conventional BIST circuits while maintaining high‐fault coverage. These BIST configurations will make a significant contribution to test cost reduction for the performance‐orientation digital LSIs, especially digital signal processor LSIs.