Date Visited: October 9, 1991
Report Author: J. Larimer
Dr. Takehiko Yoshino
Dr. Hiroshi Murakami
Dr. Takeo Suzuki
The visit began with an overview of Nippon Hoso Kyokai (NHK) presented by Mr. Izumi, Director General of the laboratory. After the introduction came discussions of the various display technologies developed and used by NHK. The primary focus of the discussion was the ongoing work on plasma display panels or PDP, but the discussion also included discussions of NHK work on polymer-dispersed liquid crystal light valves, electroluminescent flat panels, and, very briefly, HDTEC. We were given demonstrations of their 33-inch diagonal PDP, the Super-HARP Camera, and High-Vision. Following these demonstrations, discussions continued through lunch.
Nippon Hoso Kyokai, NHK, is Japan's public broadcasting corporation. The Science and Technical Laboratories were established in 1930. The mission of the laboratories is to perform "research and development required for progress in broadcasting and its reception." This mission can be subdivided into three areas: (1) "studies of putting new broadcast media into practice," (2) "studies of improved conventional broadcast services," and (3) "studies of future broadcast technology and systems."
The laboratories, located in Tokyo, have a floor space of 19,000 m2 and employ a staff of 320 individuals, 270 of whom are researchers. The annual budget is 7.7 billion yen (approx. 60 million U.S. dollars) and represents 1.3% of NHK's total budget. The laboratory has nine research divisions:
In addition, NHK Engineering Services, NHK-ES, transfers NHK expertise and technologies to the private sector. They support and provide services for:
Some of the companies and organizations that participate with NHK in joint development and/or cooperate in holding an exhibition are All Nippon Airways, Matsushita Electrical Industrial, Oki Electric Industry, Sanyo Electric, Canon, Hitachi Chemicals, Hitachi Denshi, Mitsubishi Electric, NEC, Nippon Steel Corp., Sony, Sumitomo Electric, Toshiba, JVC, Yamaha, Astrodesign, Toppan Printing, Leader Electronics, Shima Seiki, the Broadcasting Technology Association, Mietec, Seiko-Epson, and the Railway Technology Research Institute. This list was taken from "NHK Technology Open House at NAB '91" and is not exhaustive.
Recent research areas include satellite broadcast transmitters, shaped beam antennas, mobile receivers for DBS, digital DBS systems, large flat-panel display technology for HDTV, large-scale integration (LSI) for television receivers, compact and lightweight charged coupled device (CCD) cameras, wireless cameras for real-time broadcast systems, low-light extremely sensitive cameras based on high-gain avalanche rushing amorphous photoconductor (HARP), high-quality sound synthesizing, digital VTR cameras and editors with a 1/2-inch tape format, FM multiplex broadcasting for mobile and portable reception and display systems, optical cable television, 3D television with and without glasses, super surround audio, machine-based natural language translation, and surface recovery from multiple-look data using neural networks.
On the basis of a series of experiments (Hatada, Sakata, & Kusaka, 1980), NHK believes that large screen areas are required to evoke the sensation of realism in telecommunications. To achieve the goal of realism, NHK has been developing large flat- panel display devices that will ultimately be larger, thinner, and lighter than current CRT technologies. We were shown two plasma display panels (PDPs) developed at the NHK laboratories in conjunction with several Japanese companies. We also discussed a small full-color electroluminescent panel and a polymer-dispersed liquid crystal light-valve projector.
The largest PDP we were shown has a 33-inch diagonal with a 4 by 5 aspect ratio. The panel size and aspect ratio were selected because of a limitation on the active printing area of the thick-film printer installed for the project. Subjectively the device had good color and motion rendering, although the image content was very limited. It would have been informative to see a high-contrast moving target on a uniform background, but this image sequence was not available at the demonstration.
A paper by Murakami et al. (Ref. 5) describing the device stated that there were 800 by 1024 cells arranged in a quad RGBG pattern. The two green picture elements within each quad RGBG pixel reproduce independent information that corresponds to the information in the scene at the corresponding point on the screen. Thus the screen image has twice the resolution of the red or blue image. The scene sampling pattern of the images is also somewhat different due to the RGBG pixel geometry. There are 400 by 512 RGBG pixels; however, because of the independence of the two green subelements the spatial resolution is greater than 400 by 512. Gray scale was reported to be 256 levels per cell. The peak white luminance was reported to be 20 ft-lamberts. The display we saw subjectively appeared to have an average luminance value of around 6 ft-lamberts. A thick-film printing technique was used to manufacture the panel. Once perfected, this type of manufacturing should be relatively simple and potentially inexpensive. The 25-inch diagonal PDP that we were shown had excellent contrast and brightness.
A low-resolution 2.5-inch electroluminescent panel was also discussed. We were given a paper by Tsuchiya et al. (Ref. 4) that appeared in ITEC '91 and described that display. Finally, a polymer-dispersed liquid crystal light-valve projector was discussed. This was a three-color separation projector system similar in optical design to the GE light valve. The PDLC is addressed by a write light that scans the image plane, changing the light- scattering characteristic of the PDLC. A paper by Takizawa, Kikuchi, and Fujikake that described this device appeared in the SID '91 Digest (Ref. 3).
We were given a demonstration of an NTSC camera, an extraordinarily sensitive camera with 2/3-inch HARP tubes that use the avalanche multiplication principle. We also saw a hi-vision demonstration of a recent full solar eclipse photographed through a telescope using an HDTV camera with 1-inch HARP tubes. The camera's performance in sensitivity and spatial resolution, combined with the high-resolution wide-screen hi-vision CRT display, made an extremely impressive and remarkable demonstration.
Flat-panel technologies will play an important role in the broadcast television of the future. The types of information that will be available through broadcast media will increase in the future, and the distribution of service will also increase. Television will be available in public transportation systems such as buses, trains, and airplanes. Our hosts predicted that large, thin, and lightweight plasma display panels will be in the marketplace by the end of the decade. At a future date LCD technology will be used for direct-view midsize television. LCD projectors will also be used in future television systems.
NHK will aid these trends by codeveloping with private industry many of these technologies. It also cooperates with university students by providing work/study experiences in its laboratories and by providing technology and fabrication facilities not otherwise available to them. NHK does not directly provide monetary support for university-based research. Government-sponsored consortia such as HDTEC and Giant Electronics Technology Corporation also help to develop new enabling technologies.