From Visible Light to Infrared: A Brief History of the Remote Control

The television remote control is one of those everyday objects we use almost without thinking about the technology and history behind such a simple gesture as changing a channel or muting the sound without leaving the couch.

Its evolution, however, was anything but straightforward.

From wired controls to visible light, from ultrasonic sound to infrared and digital coding, each generation solved some of the problems of the previous one while inevitably introducing new limitations.

From a Cable Across the Living Room to Wireless Control

The story begins in 1950 with the Zenith Lazy Bones, an appropriately named wired remote control.

A physical cable ran from the viewer to the television set. Pressing the buttons operated a motor inside the TV, mechanically rotating the tuner clockwise or counter-clockwise to change channels and also allowing the set to be switched on or off.

It offered unprecedented convenience, but the long cable crossing the living-room floor quickly became an obvious disadvantage and a potential tripping hazard.

The next objective was therefore clear: remove the wire.

Zenith Flash-Matic: Controlling a TV with Light

In 1955, Zenith engineer Eugene J. Polley developed the Flash-Matic, one of the most distinctive devices in the history of consumer electronics.

Its green, flashlight-like body looked more like a science-fiction ray gun than what we would now recognise as a remote control.

Instead of transmitting an electrical signal through a cable, the Flash-Matic projected a directional beam of visible light toward four photosensitive elements positioned around the television screen.

By aiming at different corners of the TV cabinet, the viewer could control functions such as power, mute and channel selection.

The principle was ingenious, but visible light created a fundamental problem: the receiver also had to operate in a room already filled with light.

Sunlight and changes in ambient illumination could therefore interfere with the photosensors and cause unwanted operation of the television.

A wireless solution had been achieved, but another problem had immediately appeared.

Zenith Space Command and the Ultrasonic Era

Only a year later, Zenith introduced a radically different approach.

The Space Command, developed by the team led by Dr. Robert Adler, replaced light with ultrasonic sound.

The original transmitter did not even require batteries.

Pressing a button released a small mechanical hammer that struck a precisely dimensioned aluminium resonator. Different resonators produced different ultrasonic frequencies in the region of 40 kHz, well above the normal range of human hearing.

A specialised receiver inside the television detected and discriminated those frequencies to determine which command had been sent.

This mechanical construction also explains the nickname that would become associated with remote controls for decades: “the clicker.”

The ultrasonic system solved the sunlight problem of the Flash-Matic and avoided the wall-penetrating behaviour that made radio-frequency control undesirable for television sets placed in neighbouring homes.

But ultrasound introduced its own engineering challenges.

Metallic noises such as jangling keys or coins can contain strong ultrasonic components. The receiver therefore required filtering and integration circuits capable of distinguishing a genuine, sustained command frequency from short and irregular bursts of household noise.

Despite these difficulties, ultrasonic remote control proved remarkably successful and remained an important television technology for roughly a quarter of a century.

From Solid State to Infrared

During the 1960s, solid-state electronics gradually replaced vacuum-tube circuitry.

Remote controls could become smaller and battery powered, while ultrasonic signals could now be generated electronically rather than by mechanically striking resonant metal rods.

By the end of the 1970s and the beginning of the 1980s, however, television itself was becoming much more complex. Cable television, electronic tuning and additional functions required far more commands than the narrow ultrasonic approach could conveniently provide.

The industry therefore moved toward infrared remote control.

An infrared LED emits radiation in the near-infrared region of the electromagnetic spectrum. The LED is switched rapidly using a carrier typically in the range of a few tens of kilohertz, while digital information is encoded onto that modulated optical signal.

Photodetectors, electronic filters and dedicated integrated circuits made it possible to build increasingly inexpensive and reliable receivers while supporting many more commands than the early systems.

This combination of invisible light and digital coding established the basic architecture of the conventional television remote control that would dominate consumer electronics for decades.

Watch the Video

This video presentation was created with NotebookLM using a selected collection of original patents, scientific papers, technical documentation and historical sources.

It provides a general introduction to a new series of Giux-Lab articles dedicated to the history and technology of remote controls.

Future articles will examine individual systems in greater detail, including their original patents, electronic circuits, components and physical operating principles.

The first in-depth article will focus on the 1955 Zenith Flash-Matic: the remarkable green “ray gun” that controlled a television with visible light and became one of the most recognisable symbols of the early history of wireless remote control.

Image credits

The image of the Zenith Flash-Matic used in this article comes from the Science Museum Group Collection, object no. 2019-368, and is used under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence.

Source: Science Museum Group, “Zenith Flash-Matic remote control”, Science Museum Group Collection Online.