His next enhancement was a battery-less version that used high frequency ultrasound. The buttons struck one of four lightweight aluminium rods inside the remote (much like a piano’s keys hit the strings). A receiver inside the interpreted these high-frequency tones and switched channel, etc.
By the 1960s, Adler had moved to electronically-generated ultrasonic signals.
It was only in the 1980s that TV remotes moved away from ultrasound and over to Infrared light control.
Why am I telling you this?
Well the IEEE Edison Medal holder (1980) and Emmy award winner (1997) died this week on Thursday 15 February. Aged 94, he had filed his latest patent for touch-screen technology only two weeks ago on 1 Feb.
His wife, Ingrid, said Adler wouldn't have chosen the remote control as his favourite invention. In fact, he didn't even watch much television.
“He was more of a reader,” she said. “He was a man who would dream in the night and wake up and say, ‘I just solved a problem.’ He was always thinking science.”
Adler wished he had been recognized for more of his broad-ranging applications that were useful in the war and in space and were building blocks of other technology, she said, “but then the remote control changed the life of every man.”
The IEEE’s 1980 biography of Adler finishes with the remark:
“One incident is characteristic. When sent to Moscow as a member of the IEEE delegation to the Popov Society Meeting in 1969, he learned Russian so that, as a goodwill gesture to his hosts, he could present his paper in their language.”