As a result of improving the luminous efficiency in Plasma Display Panels (PDPs),the emission state or distributions in a co-planar structured AC-PDP were investigated as a function of time and position of the electrodes with respect to phosphor-visible light, Xe-infrared light and Ne-visible-red light using a Streak Camera.
It has been believed that the emission of PDPs takes place at the cathode site alone. However our observation revealed that at the anode site of a comparatively large sized cell:
Furthermore, inside the Xe light emitting area the standing striation structure was observed to be similar to the striation seen in a positive column.
Multilayered-type organic electroluminescent (EL) devices emitting white light were fabricated. The device having an ideal white chromaticity coordinates of CIE x,y = 0.33, 0.35 showed an external quantum efficiency of 1.19 % when the current density was 1 mA/4 mm2. It took almost 400 hours to become half value from the initial luminous intensity of 300 cd/m2 when the device was driven by a constant current in vacuum.
The EL spectra changed with the increase of the applied current density to the device. There was also a spectra change with the passage of time when the device was continuously driven under a constant current . In both cases, the red part of white emission spectra decreased and the CIE coordinates shifted to the blue direction.
The authors have developed a projector using a photo-conductive liquid crystal light valve (PCLCLV). It uses a 1.1 inch TFT-LC-panel and LEDs for addressing, a metal-haride-lamp (250 W, DC) and two dichroic mirrors. It can project a video-rate full color picture up to 100 inches diagonal.
The authors carried out simulations taking into account the luminance radiation directivity distribution of a lamp and designed the light-source
system. The development of a liquid-type polarized-beam-spliter and correction of astigmatism by a cylindrical lens helped to obtain a bright ( 650 lumen) and distinct ( 60 % at 400 TV lines-MTF) image.
The switching beam deflection of 0.16 micro meter with the switching time of less than 100 nsec. was measured by a tightly focused laser interferometric method. Observed turn-on threshold voltages were more than 30 V, and the on/off hysteresis widths were from one third to two thirds of its threshold voltage.
The memory function was confirmed by applying the hold voltage of 25 V following on the writing pulse with the duration of 2 msec. and the amplitude of 32 V. A holding period of 2 msec. or longer has resulted which will lead to usage as an AM display device.
The authors have developed a 3D-CUBE System and installed three systems in the Synthetic World Zone at the Aizu University. The system has 160 a inch diagonal screen, composed of sixteen rear-projection display units, each one being referred to as CUBE.
The junction borders of the individual CUBE units which used to appear as black stripes are made invisible.
The multi-scan 3D-CUBE system uses short afterglow CRTs and LCD shutters. The crosstalk of the system in 3D mode is less than 25 dB.
We developed a new system for alpha wave entrainment by recorded photic stimulation which has a relaxation effect and will introduce the user to sound sleep.
The alpha wave during sleep latency fluctuates its frequency, repeates its appearance and disappearance several times, and soon disappears completely. Such alpha wave data characterized by the flequency fluctuations are then taken in the photic signals generated by a photic-feedback. These signals are recoded in a memory and then replayed so that the brain wave pattern during the sleep latency is reproduced intending to reduce his/her arousal level.
The authors have developed an algorithm that defects the sleeping point and could idetify the sleeping point using the appearance rate of the burst alpha wave.
We definethe sleep latenncy as the three minutes prior to the point of sleep.
To test the feasibility of such an effect, we conducted a test for 28 adults who have a tendency of insomnia. As a result, we confirmed that there were improvements in such areas as the ease of getting to sleep, the perceived quality of sleep and the integrity of behavior following wakefulness.
The device incorporating the above mechanism is more suitable for use at bedtime compared with a conventional photic-feedback system because no annoying brain wave sensors need to be attached during the reproduction of the signal.
As a core member of the DVD group,we have been engaged in working out the DVD physical format specifications.
The key point technologies of the specifications are the following:
0.6mm thick substrate, dual layer disc(one side reading), powerful error correction code best suited for data ROM media, and 8/16 modulation.
The format also takes compatibility amongall types of the DVD media into account.
Combining these technologies, we have realized a capacity of 4.7 GB with a read-only single layered disc and 8.5 GB with a dual layer disc.
DVD video spcifications specify video application in the DVD_Read Only specifications by which many functions are realizable, specific to DVD, that have not being provided by any existing formats. They canbe applied to a wide range of purpose such as movies, materials for TV broadcasting use, Karaoke, music video, interactive media and games.
The authors will outline the DVD_Video Logical Format, more specifically about its volume data structure and features and data structure of the Video Application.
A Karaoke format has been proposed making use of DVD. More than two hours of high quality moving picture and eight channel audio playback are available with DVD. DVD being applied for Karaoke system, it can provide functions non-existing in any conventional system such as automatic voice selection, retrieval by texts and so on.
The format helps improve user friendly operations through using simplified scheme like one bouton direct selection.
A new modulation scheme, called 8/16 Modulation, has been adopted for DVD system. The 8/16 Modulation tranforms 8 data bits into 16 channel bits. Minimum recording pit length is 3T and maximum recording pit length is 11 T, where T is a channel bit length. Comparing with Eight to Fourteen Modulation(EFM) used in Compact Disc(CD), the new scheme can increase information density by 7 %. Sync pattern is selected as a unique pattern that doesn't appear in modulated codes, and its length is 14 T. The DC reduction components of the new modulation are decreased by a newly devised DC reduction technique. The 8/16 Modulation, whose DC components are less than those of the 8/15 Modulation, has been adopted chiefly because stability of the system takes over the information density.
To cope with a high recording density such as in DVD, we need reliable decoding for its playback. The authors therefore have adopted a Viterbi decoding scheme and developed the decoding circuit thereof best suited for DVD. By utilizing the nature of the recording code of DVD, the circuit is augmented in the decoding power and it has been downsized. It is composed of 3000 gates and works at a clock rate of 30 MHz.
Decoding performance has been checked by both simulation and experiment in terms of recording density, S/N ratio and skew margin. Both results showed better performance with the Viterbi decoding than with the conventional bit by bit decoding. The Viterbi decoding was confirmed to be effective in the DVD system.
A DVD pre-mastering data transfer system has been developed. The input media are optionally selected from among Pioneer's DLD(Digital Laser Disc), DEC's DLT(Digital Linear Tape), and Hard Disc with SCSI interface. The host computer reads the DVD logically formatted data from the input media at a maximum speed of the device, changes the data rate as requested by the LBR(Laser Beam Recorder), performs physical formatting and transfers data to the LBR. The maximum data transfer rate is as 3 times that of the playback speed(assuming as 4.7 Mbps average), so that a 135 minute motion picture is recorded on in about 45 minutes. Physical data errors are checked in the glassmaster cutting process. With the DVD decoder this system is able to emulate the DVD Player.
A compact Laser Beam Recorder was developed. Track pitch error on the disc mastered by this machine measured within specification which is ±0.03 µm. A newly developed high rigidity air bearing spindle motor, in conjunction with new driver was introduced for this purpose, based on the observation of rotation center fluctuation. Optical base feed servo system was also optimized by increasing the resolution of its laser transducer system. SHG laser diode and finite I-O objective lens were introduced to build short optical path and for integration of optics. For the control system, FPGA technology was introduced to reduce the initial cost. This LBR system only requires 100 VAC which reduces both initial and running cost.
The optimum DVD mastering process has been developed. On the basis of the mastering process for "Alpha" disc(Pioneer digital disc originally for karaoke use. Contains 60 minutes of motion pictures (2.1 GB of digital data) on 12 cm disc by adopting the MPEG1.), super resolution photoresist was used and the cutting conditions, the developing method and so on, were optimized to cope with the higher density.
A DVD(Read-only Single-layered) replication process and mass production materials have been developed.
In the molding process, injection-compression molding parameters were established to keep high-density duplication performance, low tilt angle and low birefringence.
In the over-coating process, new material was developed which create less warpage than ordinary CD material.
In bonding process, UV adhesive was developed to minimize warpage under high temperature and humidity.
This paper is an outline of the Dual Layer Disc, especially it's structure, methods of manufacturing, and differences between the Dual Layer Disc norm and the Single Layer Disc's counterpart. The playback method technology will also be discussed.
For realization of the Dual Layer Disc, it is important to optimize the reflective index of the half-mirror layer, the thickness of the substrate and the thickness of the space layer.
For playback, one out of two information layers can be selected easily by adjusting the focusing using a technique similar track jump. Good quality signals with less than 7 % jitter(Sigma/Tw) from each layer have been obtained.
DVD Dual Layer Discs applied with Dry Photopolymer Film and Ag semi-reflective layers were examined.
The recorded signal characterization of the discs which used Dry Photopolymer Film to space layers was almost equal to that of the Liquid Photopolymer. Furthermore, it proved able to control the thickness of the spacing layer of the Dry Photopolymer Film more than the Liquid Photopolymer.
The semi-reflective layer was examined while substituting Au for Ag. Optical characterization of the Ag semi-reflective layer was almost equal to Au at Lambda = 650 nm. Durability tests (signal characterization with test conditions of 60 °C60 %RH for 48 hours plus 70 °C60 %RH for 48 hours plus 70 °C60 %RH for 48 hours ) show that reflections from the Ag semi-reflective layer deteriorated drastically.
The authors have developed a write once type medeia called 'DVD-R' and the recording system using such a disc, which is fully compatible with DVD-ROM disc.
The DVD-R disc is made of two transparent plastic substrates each of whose thickness is 0.6 mm and glued together such that the recording layer made of organic dye material is protected.
The optical pick up head for recording and reading has been developed.
The optical output power is 10 mW using a high power laser diode whose wave-length is 635 nm.
As a result of the recording, the user data capacity of 3.9 GB perside of a 120 mm diameter disc has been confirmed.
A byte error rate of 1×10-3or less has been obtained under the following conditions:
Recording Power : 6.7 -9.0 mW
Defocus(rec & playback) : ±1.3µm
Playback jitter of 15 % or less (Byte Error Rate = 5 × 10-3) has also been confirmed under the following conditions for the disc tilt.
Disc tilt(playback) : ±0.75 deg(radial)
: ±0.55 deg(tangential)
The Write Once Media(DVD-R) which is an optical disc has the backward compatibility with ROM type DVD has been developed. New type organic dye for use a short wavelength laser diode ( wave-length = 635 nm), is used as the recording material. As a result of evaluated recording character, C/N ratio of 50 dB or greater have been obtained. We also observed a clearly opened eyepattern from marks written by the 8/16 modulation code.
We set about developing a DVD checker which automatically measures high frequency (HF) signals, servo signals, byte error rates and track radius eccentricities.
Target specifications for the checker are as follows.
We try to follow 2. and 3. above step by step.
The rewritable type "DVD-RAM" disc using phase-change overwritable media with a capacity of 2.6 GB/side is being considered for creating of specification. Taking such things into account as the compatibility with the DVD-ROM media, manageability of random and sequential data files, and high capacity, the key specifications of the DVD-RAM are proposed as set out bellow:
New methods are proposed for nonstationary signal analysis and those are proved to be advantageous for practical reasons.
A stationary signal is, generally, analyzed either in time domain or in frequency domain. But a nonstationary signal must be represented simultaneously in the time-frequency two-dimensional plane because it's frequencies evolve with time. For a time-varying signal, whether a deterministic transient or nonstationary random, the use of a discrete pseudo-Wigner distribution(pseudo-WD) is suitable. To obtain several concrete results, WD is applied to evaluate the low resonance frequencies , and to analyze the impact-sound signals.
Application of the WD, however, is often complicated by the occurrence of interference terms. Those terms are irrelevant to any physical properties of the original signal, and prevent us from correct interpretation of analytic results. Therefore, to extract reliable information from a signal, these superfluous terms must be omitted. In this study, the mechanism of interference is elucidated and effective measures are taken to exclude them. Then, a newly revised WD, called RID(Reduced Interference Distribution), is proposed. To derive minute informations from low S/N signals, the RID is applied to cross-WD which analyzes two different time series in the time-frequency two-dimensional plane. One of the two signals is denoted as the reference function. Both simulated and such instrumented signals as impact sounds of a sandwich steel sheet and voices, are analyzed by the CRID which is a RID applied to cross-WD.
Alternatively, another method was developed in this study. It makes use of the block adaptive filter both to suppress the interference terms and to evaluate them quantitatively. This method is called BLMS-WD, or Block LMS WD, because Least Mean Squares, LMS, algorithm is applied in frequency domain. This method provides accurate time-frequency representation imposing no restriction on both time and frequency resolutions. It is discussed in this paper.
Both simulated Chirp signals and an instrumented sound signal obtained from a concert hall are analyzed with RID, BLMS-WD and other methods. Comparisons were made. As a result, it is clear that the Choi-Williams method and scalogram which is the energy spectrum of Wavelet, gave better results than other traditional methods. It was also clear that the best description was obtained from the RID. BLMS-WD was the most suitable method to correspond with the auditory perception, of say, a concert hall reverberation while a spectrogram is a better, fit for conventional analysis.
The final stage of this study, a unified framework of a joint time and frequency representation was accomplished.
We conclude that several valuable methods for nonstatioary signal analysis were developed in this study, and that the characteristics of those methods were investigated theoretically. Their abilities were verified by analyzing both simulated and instrumented signals. This analysis present us with very valuable information in the signal, which have not been obtained from existing traditional analysis.
The Generalized Harmonic Analysis (GHA), which is an effective time-frequency analysis methods, has been applied to nonstationary signals, such as a piano tone and a singing voice. Using this method, the time-varying spectra, as well as the pitch, was found to be visualized with high frequency resolution. The GHA method does not have the truncation effects, and is not as constrained by the serious drawback, that is, time-frequency resolution trade-off which can be seen mainly using the short-time Fourier transform(STFT).
We have studied a method to analyze the jitter on playback signals of read only type disc. This system measures the jitter of each edges as a pattern of preceding run-rength. And it can classify the jitter to the noise and intersymbol interference components, in order to analyze it in detail. Furthermore, the system can estimate the transfer funtion of the read and write system from the measured data.
Using the result of analysis system, we also tried to reduce intersymbol interference jitter by the recording compensation. As a result, we confirmed availablility of the recording compesation.
We developed "Link Dijkstra Algorithm" which finds routes appropriate for traffic regulations, using a path finding database based on an undirected link. Also, we built "Layered Path Finding Database" for fast calculation with a small amount of memory in the Car Navigation System.
Then, we took "the searching method with a multiple Proposed Point" for calculating more reasonable path with the "Layered Path Finding Database".
Several Conditional Access methods for use in a digital satellite broadcasting system have been investigated.
In the process of developing a digital satellite broadcasting receiver which complies with the conditional access specifications proposed by the European Project for Digital Video Broadcasting, the author has established the conditional access methods necessary for constructing a preexisting European digital satellite broadcasting system.
This paper reports that the conditional access system design as one of the most important technologies within the digital satellite broadcasting systems configuration.
A descrambler IC has been designed for the European digital satellite broadcasting receiver. The author has investigated scrambling/descrambling methods and their algorithms for this development.
The scrambling/descrambling methods comply with both levels of the MPEG2 system layer: Packetized Elementary Stream (PES) and Transport Packet (TS). The former is a variable length scheme and the latter is a fixed length scheme. A data encryption scheme has been adopted in the algorithms for some sensitive parameters to ensure the scramble/descramble system is security.
Some of the specifications for the IC realized by the above technology are the following.
A prototype decoder unit of Digital Audio Broadcasting (DAB) receiver has been developed. This decoder can decode the DAB signal on the EUREKA 147 3rd generation experimental format. The performance of this decoder has been evaluated in laboratory and field tests.
Through these tests, it was found that the audio signals could be reproduced normally even in conditions which included the effects of multipath fading. These tests have thus confirmed the advantages of the DAB system for reception in mobile receivers.