The earliest remote controller used to control TV was invented by Zenith, an American electrical appliance company, in 1950. It was wired at first.
1955, Zenith company invented a wireless remote control device called "Flashmatic". But this device can't tell whether the light beam comes from the remote control, and it must be aligned to control it.
1956, another inventor named Rob Adler developed a remote controller named ZenithSpaceCommand, which is also the first modern wireless remote control device. He uses ultrasonic waves to adjust the channel and volume. The frequency of each key is different, but this device may also be interfered by ordinary ultrasonic waves. Some people and animals (such as dogs) can hear the sound from the remote control. By 1980, when semiconductor devices for emitting and receiving infrared rays were developed, they gradually replaced ultrasonic control devices. Even with the development of other wireless transmission methods (such as Bluetooth), this technology continues to be widely used until now. ]
remote control