The Telegraph notes the passing of a cultural giant:
Robert Adler, who has died aged 93, was the co-inventor of the television remote control.
Although an earlier version existed - it used cables and was called Lazy Bones - in 1956 Adler and a colleague came up with a wireless version using ultrasonic sound.
....In 1955 the American company for which Adler worked, Zenith, produced the Flashmatic, a wireless remote that was basically a flashlight pointed at photo cells located at the corners of the television set; unfortunately the photo cells reacted to sunlight as well as the remote.
Adler's solution was to have the remote communicate with the set not by light but by sound, specifically ultrasound, at frequencies higher than the human ear can hear.