Pursuit of Future Television
The Tokyo Olympic Games in 1964 made a strong impression on the public and demonstrated that the level of TV technology in Japan was the highest in the world. Those in TV related industries in Japan were envisioning the next generation of TV. STRL initiated studies on high-definition television (HDTV) in 1964.
Research followed two tracks. One was to visualize “future TV” from a thorough investigation of what was to be expected of the future television system, as well as the physical conditions of the system. The other approach was to reexamine the kind of display, or video, to determine the easiest and most desirable media for humans to watch. This involved a thorough study of human audio-visual characteristics and psychology. Among a number of options, STRL decided on high-definition TV as the main direction for its research, calling it simply HDTV. In 1985, this system was named Hi-Vision.

16:9 Ratio Derived from Human Audio-visual Characteristics
Regarding the ratio between height and width of the display, the aspect ratio, evaluations made using a slide projector revealed that the most desirable aspect ratios are 5:3 or 6:3, wider than the 4:3 ratio then used for a standard TV display. Later, the aspect ratio 16:9 was decided upon, in consideration of its compatibility with movies.
From 1965 to 1975, advances were made in determining the necessary number of scanning lines for HDTV. During this time, the decision to go with an interlaced scanning system was also made. These involved both film simulations and actual TV systems.

Developments in Imaging, Recording, Transmission, and Displays
STRL determined NHK’s provisional studio standard for HDTV around 1970. This standard was 1125 scanning lines, a 2:1 interlaced ratio, and a 5:3 aspect ratio. Based on this standard, work was initiated on imaging systems, recording devices, transmission systems, and large-screen display PDPs.
In 1969, the first experimental high-definition TV system was exhibited at the STRL Open House. It used a 1.5-inch vidicon and a 27-inch black-and-white Braun tube. For an image pickup tube, a 2-inch return beam Saticon was also developed.
STRL began the development of a color camera system around 1970, resulting in a small, low power consumption, 2/3-inch Saticon camera in 1985, and a high-sensitivity high-definition TV camera with a 2/3-inch HARP (High-gain Avalanche Rushing amorphous Photoconductor) tube in 1988, which made capturing images outdoors at night feasible. In 1998, an HDTV camera using a HARP tube was produced on a commercial basis.

1. HDTV and audio-visual properties
2. Exhibition in the United States (1981)