NHK Science and Technical Research Laboratories

Tokyo, Japan

NHK Science and Technical Research Laboratories

Tokyo, Japan
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Mitsuhashi T.,NHK Science and Technical Research Laboratories
19th Annual SMPTE Television Conference: Components of the Future | Year: 2015

The HDTV must satisfy the visual and psychological requirement of the viewers. Electro-cinematography, printing, application to other imaging systems, ease of manufacturing the equipment and cost are also important factors. © 1985 Society of Motion Picture and Television Engineers, Inc.


Suna Y.,Tokyo Institute of Technology | Nishida J.-I.,Tokyo Institute of Technology | Fujisaki Y.,NHK Science and Technical Research Laboratories | Yamashita Y.,Tokyo Institute of Technology
Organic Letters | Year: 2012

Organic field-effect transistors with hydrogen-bonded diketopyrrolopyrrole- thiophene co-oligomers were fabricated by a solution-process method with annealing at 200 °C, showing ambipolar charge-carrier transfer with field-effect mobilities up to μ h = 6.7 × 10 -3 cm 2 V -1s -1 and μ e = 5.6 × 10 -3 cm 2 V -1 s -1. © 2012 American Chemical Society.


Ando A.,NHK Science and Technical Research Laboratories
Acoustical Science and Technology | Year: 2012

A coding and transmission method for three-dimensional (3D) sound was investigated to realize the broadcasting of 22.2 multichannel sound, which is the audio part of Super Hi-vision. The proposed method was evaluated by performing experiments using the 22-channel signal of 22.2 multichannel sound without two low-frequency effect channels. The loudspeaker positions of the eight-channel system were set as (30,0), (90,0), (150,0), (210,0), (330,0), (60,45), (120,45) and (90, -30). 14 directional functions were used, whose principal axes were directed to (0,0), (30,0), (60,0), (90,0), (120,0), (150,0), (180,0), (270,0), (45,45), (90,45), (135,45), (215,45) (335,45) and (0,90) in degrees. In the experiment, nine sound materials of about 10 s length were used. One of the materials was used for training W s. The number of iterations in the simulated annealing was set to 10,000. For sound materials other than Birds, a significant power reduction was obtained, suggesting that the spatial characteristics of 3D sound can be learnable.


Ando A.,NHK Science and Technical Research Laboratories
IEEE Transactions on Audio, Speech and Language Processing | Year: 2011

In this paper, we describe a new method for converting the signal of the original multichannel sound system into that of an alternative system with a different number of channels while maintaining the physical properties of sound at the listening point in the reproduced sound field. Such a conversion problem can be described by the underdetermined linear equation. To obtain an analytical solution to the equation, the method partitions the sound field of the alternative system on the basis of the positions of three loudspeakers and solves the local solution in each subfield. As a result, the alternative system localizes each channel signal of the original sound system at the corresponding loudspeaker position as a phantom source. The composition of the local solutions introduces the global solution, that is, the analytical solution to the conversion problem. 22-channel signals of a 22.2 multichannel sound system without the two low-frequency effect channels were converted into 10-, 8-, and 6-channel signals by the method. Subjective evaluations showed that the proposed method could reproduce the spatial impression of the original 22-channel sound with eight loudspeakers. © 2011 IEEE.


Masaoka K.,NHK Science and Technical Research Laboratories | Nishida Y.,NHK Science and Technical Research Laboratories
Optics Express | Year: 2015

Assessing the coverage of the color space of Recommendation ITU-R BT.2020 (Rec. 2020) has become increasingly important in the design of wide-gamut displays, and an appropriate metric for measuring the display gamut size is urgently needed. Display manufactures calculate the area ratios of their displays' RGB triangles to a standard RGB triangle in the CIE 1931 xy or CIE 1976 u′v′ chromaticity diagram to indicate the displays' relative gamut size. However, they typically fail to mention which of the two diagrams the metric is based on. This paper shows that the ratios calculated in the two chromaticity diagrams are highly inconsistent, and that the Rec. 2020 area-coverage ratios for wide-gamut displays in the xy diagram are much more correlated to the Rec. 2020 volume-coverage ratios in some color-appearance spaces than the Rec. 2020 area-coverage ratios in the u′v′ diagram. This paper recommends the use of the xy diagram for areacoverage ratio calculations for wide-gamut displays. © 2015 OSA.


Masaoka K.,NHK Science and Technical Research Laboratories
Optics Letters | Year: 2010

A fast and accurate model to compute optimal colors under a given illuminant is introduced. The model estimates the reflectance (transmittance) distributions of optimal colors, which is bandpass (Type 1) or bandstop (Type 2), at a given luminance factor with user-specified small tolerances for the bandwidth (e.g., 10-10 nm). The tristimulus values of the optimal colors are obtained by using trapezoidal integration of the product of color-matching functions and illuminant spectrums sampled with small wavelength steps instead of performing summation of the product values. Selecting the distribution type whether Type 1 or Type 2 is avoided in the algorithm to reduce computing cost. Some optimal color solids computed by a MATLAB program have been demonstrated. © 2010 Optical Society of America.


Sugawara M.,NHK Science and Technical Research Laboratories | Masaoka K.,NHK Science and Technical Research Laboratories
Proceedings of the IEEE | Year: 2013

Ultrahigh-definition television (UHDTV) is now being studied as the most promising candidate for next-generation television beyond HDTV. It consists of extremely high-resolution imagery and multichannel 3-D sound to give viewers a stronger sensation of reality. Various aspects should be taken into account when determining UHDTV image format. Of those, it is believed that user visual experience is some of the most important aspects to be considered. This paper describes the studies conducted on the relationship between image format and visual experience of UHDTV. © 1963-2012 IEEE.


Masaoka K.,NHK Science and Technical Research Laboratories | Nishida Y.,NHK Science and Technical Research Laboratories | Sugawara M.,NHK Science and Technical Research Laboratories
Optics Express | Year: 2014

The wide-gamut system colorimetry has been standardized for ultra-high definition television (UHDTV). The chromaticities of the primaries are designed to lie on the spectral locus to cover major standard system colorimetries and real object colors. Although monochromatic light sources are required for a display to perfectly fulfill the system colorimetry, highly saturated emission colors using recent quantum dot technology may effectively achieve the wide gamut. This paper presents simulation results on the chromaticities of highly saturated non-monochromatic light sources and gamut coverage of real object colors to be considered in designing wide-gamut displays with color filters for the UHDTV. © 2014 Optical Society of America.


Ando A.,NHK Science and Technical Research Laboratories
Proceedings of Meetings on Acoustics | Year: 2013

In sound reproduction with accompanying pictures, the localization of sound on or behind the flat-panel display is problematic because a loudspeaker cannot be placed in such directions. To gain a stable localization, the use of a loudspeaker array set on the frame of the display may be a solution. In general, the loudspeaker array can generate the spherical wave surface from the virtual sound source located at the center of the wave surface. However, the frequency response and the shape of the wave surface reproduced by the array sometimes deteriorate, particularly when setting the virtual sound source at a certain distance from the back of the display In this study, new parameters are introduced to scale the deterioration of the frequency response and the shape of the wave surface. A new method is then proposed, and the weighting coefficients over the array elements are generated by minimizing these parameters. The experimental result showed that the frequency response approached the flat response, although the fluctuation in the high-frequency band still remained unclarified. The shape of the wave surface was also improved making the control of sound depth possible with the frame loudspeaker array. © 2013 Acoustical Society of America.


Sugimoto T.,NHK Science and Technical Research Laboratories
Proceedings of Meetings on Acoustics | Year: 2013

A flexible sound generator based on the thermoacoustic effect was proposed for use with thin and flexible devices. The proposed sound generator was composed of three thin films made of aluminum, polyimide, and graphite for effective interaction between acoustic energy and heat. The aluminum functions as an electrode for heat radiation into the air, polyimide as a heat insulator, and graphite as a heat sink. The shape of the electrode was a rectangle. Relationship between sound pressure, applied voltage and temperature change of the electrode was modeled. Radiated sound pressure was analytically described as a function of the input signal's frequency. Experimental measurements were carried out and they showed the validity of the model in terms of radiated sound pressure estimation from the proposed structure with selected materials. Surface vibration was also observed, and it was confirmed that the proposed sound generator is vibration-free. © 2013 Acoustical Society of America.

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