Nobukazu Teranishi set out on his road to change the world when he began an undergraduate degree in physics at the University of Tokyo in 1972. Already developing an interest in semiconductors, he remained at the University of Tokyo, graduating with a Master’s degree in physics in 1978. From here, he took a job with the NEC corporation, an IT and electronics corporation in Tokyo.

While working for NEC, Teranishi was engaged in advancing image sensors and camera technology, and it was in 1980 that he invented the pinned photodiode, transforming the way we see the world.

Pinning the photodiode

A diode is a type of semiconductor. This means that under some conditions it will allow the flow of electricity through it, while under other conditions it won’t. In this way, the diode allows the flow of current in one direction only, rather like a one-way valve. A photodiode does this when it is exposed to light and is made of a typical semiconductor material such as silicon.

Teranishi’s pinned photodiode, or PPD, is a light-sensitive diode that when exposed to a light generates an electric current. It is a much more efficient photodiode than those originally used in Tompsett’s CCD imaging sensor, producing higher quality images. The improved performance of the PPD meant that the size of light capturing cells or ‘pixels’ in image sensors could be reduced, packing more of them into the same area. This resulted in a higher resolution and better quality of images.

The PPD became a crucial component in almost all CCD sensors and in the 1990s the technology was also introduced to the new CMOS image sensors.

A lifetime’s achievement

After leaving NEC at the turn of the millennium, Teranishi began working for the Panasonic Corporation, where he stayed for 13 years, developing imaging sensors for various applications. He has continued innovating in this area and holds numerous patents both in Japan and the United States. He is currently a professor at two universities in Japan, the University of Hyogo and Shizuoka University, where he is developing photon counting image sensors for visible-light x-ray.

Nobukazu Teranishi has been internationally recognised for his work in image sensor technology, receiving the Prize of the President of KEIDANREN of National Invention Awards in 1994; the Persons of Scientific and Technological Research Merits Commendation by Minister of State for Science and Technology in 1997; Progress Medals from the Royal Photographic Society and the Photographic Society of America; and the Yamazaki Teiichi Award.

On 1 February 2017, he became the first engineer from Japan to be awarded the Queen Elizabeth Prize for Engineering, being honoured for his contribution to the creation of digital imaging sensors.

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