The Zenith Radio Corporation created the very first television remote control in 1950 called Lazy Bone — it was attached to the TV by a bulky cable. The Zenith Space Command remote control went into commercial production in 1956.
This ultrasonic remote remained the dominant design for the next 25 years, and, as the name suggests, worked using ultrasound waves.
The Space Command transmitter used no batteries. Inside the transmitter were four lightweight aluminum rods which emitted high-frequency sounds when struck at one end. Each rod was a different length, to create a different sound, which controlled a receiver unit built into the television.