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NHK Laboratories Note
NHK Laboratories Note No.508 
High-Speed Tracking Control System for Broadcast-Use Optical Disk Drive
Daiichi KOIDE, Haruki TOKUMARU, Kiyoshi OHISHI*1, Kazuyoshi KURAMOCHI*1 and Toshimasa MIYAZAKI*2
*1 Nagaoka University of Technology,
*2 Nagaoka National College of Technology,
Japanese Journal of Applied Physics Vol. 45, No. 2B, pp. 1187 -1192 (2006)
A high-speed tracking control system using feed-forward control with the zero phase error tracking method (ZPET - FFcontrol) has been applied to high - data - transfer - rate and high -density optical disk drives for broad castuse. To realize high - data - transfer - rate optical disk drives,the optical head must be controlled for track - following with an accuracy of less than 9 nm during high -speed disk rotation. We compared the characteristics of the tracking accuracy of ZPET - FF control with those of conventional feedback control at 15000rpm and analyzed their frequency responses in a simulation. The results show that the ZPET - FF control is accurate and robust toward periodic disturbances at high speeds. Experimental results show that ZPET -FF control is more precise than feedback control, and the residual tracking error is suppressed to 8.02nm at a linear velocity of 18.3m/s in an optical disk drive having a blue - violet laser (wavelength : 405nm), an object lens with a numerical aperture (NA) of 0.85, and media with a track pitch of 0.32µm. [DOI:10.1143/JJAP.45.1187]
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Copyright : The Japan Society of Applied Physics

NHK Laboratories Note No.507 
Curved Ferroelectric Liquid Crystal Matrix Displays Driven by Field-Sequential-Color and Active-Matrix Techniques
Hideo FUJIKAKE, Hiroto SATO, Takeshi MURASHIGE, Yoshihide FUJISAKI, Taiichiro KURITA, Tadahiro FURUKAWA* and Fumio SATO
* R&D Department, Kyodo Printing Co.,
Optical Review , vol.13, no.1, pp.14-19(2006)
This paper describes a curved field-sequential-color matrix display using fast-response ferroelectric liquid crystal. Black matrix and transparent electrode patterns were formed on a thin plastic substrate by a transfer method from a glass substrate. While a composite film of liquid crystal and micro-polymers of walls and fibers was formed between the flexible substrates by printing, laminating and curing processes of a solution of monomers and liquid crystal, the mechanical stability was enhanced by use of multi-functional monomers to form large display panels. The image pixels of the matrix panel were driven by an active matrix scheme using an external switch transistor array at a frequency of 180 Hz for intermittent three-primary-color backlight illumination. The flexible A4-paper-sized color display with 24 × 16 pixels and 60 Hz field frequency was demonstrated by illuminating it with sequential three-primary-color lights from light-emitting diodes of the backlight. Our display system is useful in various information displays because of its freedom of setting and location.
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Copyright 1994-2006 The Optical Society of Japan (An Affiliate of the Japan Society of Applied Physics)

NHK Laboratories Note No.506 
Protective Layer for High-Efficiency PDPs Driven at Low Voltage
Yasushi Motoyama, Toshiharu Kurauchi *
* ULVAC, Inc.,
Journal of the Society for Information Display vol.14, no.5, pp.487-492 (2006)
The sustain pulse voltage of a panel for 66-kPa Ne + Xe (5 - 30%) with an (SrCa)O protective layer is 20 - 40% lower than that with an MgO protective layer. The luminous efficiency of the panel with a Ne + Xe (30%) (SrCa)O protective layer is 1.5 times that of the conventional panel with a Ne + Xe (10%) MgO protective layer; the sustain pulse voltages of these panels are almost the same. The power loss caused by panel capacitance is proportional to the second power of the sustain pulse voltage. Using the (SrCa)O protective layer for Xe (5 - 30%), the power loss is reduced by 35 - 60% compared with the MgO protective layer. It follows that, using the (SrCa)O protective layer, we can increase the Xe content with little power loss and thus achieve high-efficiency PDPs. As for MgO and CaO with Xe ions, electrons are probably ejected from only the defect states. On the other hand, as for the SrO with Xe ions, it is likely that electrons can be ejected from not only defect states but also the valance band. This seems to be the reason why the driving voltage is lower with the (SrCa)O protective layer than with the MgO protective layer.
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Copyright Society for Information Display. This paper is made available with permission of the Society for Information Display. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

NHK Laboratories Note No.505 
Spatial Distortion Prediction System for Stereoscopic Images
Kenichiro Masaoka, Atsuo Hanazato, Masaki Emoto, Hirokazu Yamanoue, Yuji Nojiri and Fumio Okano
Journal of Electronic Imaging, Vol. 15, Iss. 1, 013002 (2006).
We propose a system to calculate the spatial distortion in 3-D images based on the shooting, display, and viewing conditions. It can be used to predict the extent of the perceived puppet-theater effect and the cardboard effect. The magnitude of the spatial distortion and the extent of the puppet-theater and cardboard effects are displayed using a space grid whose size can be estimated based on the objects?f depths, calculated from the binocular parallax of the acquired stereoscopic images. This system can also be used to predict excessive binocular parallax and excessive parallax distribution. Several cases in which puppet-theater and cardboard effects are expected to be produced are presented. We also demonstrate how the proposed system might be used to predict ratings of naturalness and quality of depth.
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Copyright 2006 Society of Photo-Optical Instrumentation Engineers. This paper was published in Journal of Electronic Imaging and is made available as an electronic reprint with permission of SPIE.
One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

NHK Laboratories Note No.504
A lateral Chromatic Aberration Correction System for Ultrahigh-definition Color Video Camera
Takayuki Yamashita, Hiroshi Shimamoto, Ryohei Funatsu, Kohji Mitani, Yuji Nojiri
Sensors, Cameras, and Systems for Scientific/Industrial Applications VII, SPIE Proc. vol. 6068, 60680N, (2006).
We have developed color camera for an 8k x 4k-pixel ultrahigh-definition video system, which is called Super Hi- Vision, with a 5x zoom lens and a signal-processing system incorporating a function for real-time lateral chromatic aberration correction.
The chromatic aberration of the lens degrades color image resolution. So in order to develop a compact zoom lens consistent with ultrahigh-resolution characteristics, we incorporated a real-time correction function in the signal-processing system. The signal-processing system has eight memory tables to store the correction data at eight focal length points on the blue and red channels. When the focal length data is inputted from the lens control units, the relevant correction data are interpolated from two of eights correction data tables. This system performs geometrical conversion on both channels using this correction data. This paper describes that the correction function can successfully reduce the lateral chromatic aberration, to an amount small enough to ensure the desired image resolution was achieved over the entire range of the lens in real time.
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Copyright : International Society for Optical Engineering (SPIE)

NHK Laboratories Note No.503
Conductor Loss Reduction for Liquid Crystal Millimeter-wave Beam Former
Hirokazu KAMODA, Takao KUKI, and Toshihiro NOMOTO
IEICE Electronics Express, Vol. 2, No. 18, pp.471-476(2005)
Means of reducing the conductor loss of a liquid crystal millimeter-wave beam former were studied. The conductor loss is caused by surface currents flowing on electrodes of the beam former for applying control voltages to the liquid crystal layers. By making the electrode thickness comparable to or thinner than the skin depth, the surface currents that flow on both sides of the electrode in opposite directions cancel each other; consequently, the conductor loss can be reduced. Simulation results proved that doing so can effectively reduce the conductor loss.
Copyright The Institute of Electronics, Information and Communication Engineers.
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NHK Laboratories Note No.502
A Method of Estimating Coding PSNR Using Quantized DCT Coefficients
Atsuro ICHIGAYA, Masaki KUROZUMI, Naohiro HARA, Yukihiro NISHIDA and Eisuke NAKASU
IEEE Transactoins on Circuits and Systems for Video Technology, Vol.16, No.2, pp.251-259(2006)
A new method of estimating coding peak signal-tonoise ratio (PSNR) without the use of reference signals is presented. Although PSNR is commonly used as a measure of the picture degradation of digitally coded video, the calculation requires source signals as a reference.Therefore, the usage of PSNR is restricted to particular applications or systems. The proposed method enables PSNR estimation based on the probability density functions of quantized discrete cosine transform (DCT) coefficients extracted from an MPEG-2 bit stream. We experimented with MPEG-2 video coding bit streams under varying quantization scheme and evaluate a new method with comparing estimated PSNRs with actual PSNRs. Experimental results indicate that the determination coefficients are higher than 0.9 This method can apply to both SDTV and HDTV, and can evaluate PSNR of every frame coded by different picture types. Index Terms - Discrete cosine transform (DCT) coefficients, Laplacian distribution, MPEG-2 bit stream, peak signal-to-noise ratio (PSNR), quantization.
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Copyright [2006] IEEE. Reprinted from Transactoins on Circuits and Systems for Video Technology

NHK Laboratories Note No.501
Repeated Vergence Adaptation Causes the Decline of Visual Functions in Watching Stereoscopic Television
Masaki EMOTO, Takahiro NIIDA and Fumio OKANO
IEEE Journal of Display Technology, Vol.1, No.2, pp.328-340(2005)
To evaluate visual fatigue when viewing stereoscopic TV, a technology expected to become the broadcasting display system of the future. Wide public acceptance of stereoscopic TV awaits resolution of many issues, including visual fatigue on viewing TV images. Visual fatigue was induced using a visual function simulator, consisting of prism and lens optical systems, while viewing stereoscopic TV. We assessed subject visual fatigue through subjective reports of symptoms and by the changes in visual functions. These functions included: viewer [Js fusional break point, recovery point, accommodation step response, and visual evoked cortical potentials (VECP)]. Significant changes of some visual functions were found after watching simulated stereoscopic TV when the vergence load was heavy or when it changed over time; relative vergence limits decreased and the latency of VECP increased after watching, reflecting visual fatigue. After subjects rested, relative vergence limits recovered to pre-viewing levels. Our findings lead us to conclude that, aside from excessive horizontal binocular parallax, discontinuous changes in parallax is also a major factor that contributes to visual fatigue in the viewing of stereoscopic images. It also causes a decreased range of relative vergence, accommodation response, and a delay in the P100 latency of VECP.
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Copyright c (2005) IEEE. Reprinted from Journal of Display Technology

NHK Laboratories Note No.500
1024-QAM Demodulator Robust to Phase Noise of Cable STB Tuners
Takuya KURAKAKE, Naoyoshi NAKAMURA and Kimiyuki OYAMADA
IEEE Transactions on Consumer Electronics, Vol.51, No.2, pp.413-418(2005)
The 1024-QAM demodulator we developed for cable television networks uses a modified symbol-decision region to reduce the effects of phase noise due to set-top-box tuners. The symbol-decision region is optimized by analysis of phase noise distribution. Simulation results show that good demodulation characteristics of a 1024-QAM signal are achieved under typical phase-noise conditions. The results are verified in a field trial with a prototype demodulator and an off-the-shelf tuner.
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Copyright [2005] IEEE. Reprinted from Transactions on Consumer Electronics

NHK Laboratories Note No.499
Moire Fringe Reduction by Optical Filters in Integral Three-dimensional Imaging on a Color Flat-panel Display
Makoto OKUI, Masaki KOBAYASHI, Jun ARAI and Fumio OKANO
Applied Optics, Vol.44, No.21, pp.4475-4483(2005)
We propose a method to reduce the color moire fringes that are attributable to the structure of a color flat-panel display in integral three-dimensional imaging. The method uses two types of optical low-pass filter, diffuser and defocus. The effectivencess of the method was confirmed in an experiment. We describe a way to design these filters with moire’ s residual energy and video signal energy as indices and demonstrate the validity of the model, which combines two filters to reduce moire fringes.
  OCIS codes: 100.6890,110.6880, 330.6110
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Copyright Optical Society of America

NHK Laboratories Note No.498
Low Resistance Spin-valve-type Current-perpendicular-to-plane Giant Magnetoresistance with Co75Fe25
Ken-ichi Aoshima, Nobuhiko Funabashi, Kenji Machida, Yasuyoshi Miyamoto, and Kiyoshi Kuga
(Materials Science)
Journal of Applied Physics, vol.97, no.10-2, 10C507, 2005, [3p.]
Spin-valve-type current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) read sensors containing Co75Fe25 have been investigated. This type of sensor exhibits a MR ratio of 2.88%, which is a factor of 1.5 times larger than that of the conventional CPP-GMR sensor containing Co90Fe10 (1.98%). Three types of Co75Fe25-CPP-GMR structures were fabricated, with the following sequence of increasing etching depths: through the capping layer only (type A), through the CoFe/Cu/CoFe trilayer (type B) and through the IrMn antiferromagnetic layer (type C). The MR ratio increases with the etching depth, and a MR ratio of 3.31% was achieved for the type C sample, which is one of the largest reported MR ratios for low-resistance area product-CPP-GMR sensors. [DOI: 10.1063/1.1850835]
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Copyright (2005) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

NHK Laboratories Note No.497
Orientation of Organic Semiconductor Films on Photoreactive Polyimide Films and its Influence on Field-Effect Transistor Characteristics
Hiroshi Kikuchi, Yuichiro Uchida1, Yoshihide Fujisaki, Hiroto Sato, Hideo Fujikake, Taiichiro Kurita, Kuniharu Takizawa1 and Fumio Sato
(Material Science)
*1: Seikei University,

2005 MRS(Materials Research Society) Spring Meeting Abstract, I3.7, p.208 ( 2005 )
In this study, we have investigated the effect of surface treatment on the orientation and mobility of pentacene by using a photoreactive polyimide film to modify the gate-insulator surfaces of organic field effect transistors (OFETs). Surface modification includes a photoreactive polyimide film, presenting a passivated interface on which the semiconductor can grow. This polyimide film can control of the orientation of semiconductor by using linearly polarized deep UV (LPDUV) irradiation. Fabricated OFETs include stacked structures of Ta2O5 as the gate insulators and the photoreactive polyimide. Most of the characteristic parameters of the OFETs, such as carrier mobility and on/off current ration, have been improved by using the photo-alignment treatment achieved with LPDUV irradiation.
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Copyright 2005 Materials Research Society

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