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Oct 16, 2024

The winding path to the infrared remote control: part 1 - Electrical Engineering News and Products

October 15, 2024 By Bill Schweber Leave a Comment Today’s IR-based remote controls have little resemblance to their predecessors; it took the convergence of unrelated advances to get us here. We take

October 15, 2024 By Bill Schweber Leave a Comment

Today’s IR-based remote controls have little resemblance to their predecessors; it took the convergence of unrelated advances to get us here.

We take the ubiquitous infrared-based (IR) remote control for TVs and other household devices for granted. They are small, lightweight, run for months on a battery (some are solar-powered), reliable, and easy to use (notwithstanding the often-confusing button arrangement of many). They have become so low-cost and available that in addition to having them for use with TVs and cable, streaming boxes, or set-top boxes, even a low-end window fan ($30-$50) comes with one, as does a basic window air conditioner ($100).

Most lack a display, which can be good or bad depending on circumstances, application, and user, but it increases battery life and costs less. They come in a bewildering area of keyboard layouts, arrangements, and functions, often with a key dedicated to each function (Figure 1).

Other remotes go the “minimalist” route with few buttons but instead make extensive use of the on-screen pull-down menu (Figure 2). Regardless of design, the basic connectivity between the remote control and what is being controlled is the same: using a modulated optical signal in the infrared range.

Since many households have three, four, or more remote controls in their main “media area,” some advanced IR units can be programmed to handle multiple devices simultaneously. Thus, a single remote control can support a TV screen, tuner, set-top box, Roku or Slingbox, and more.

Note that basic remote controls are also used for household devices other than a TV or its peripheral devices. However, TV-focused remotes drove the development of the technology, which was then adapted to these other non-media applications.

Also, there are RF-based remote controls with more range and reach and smartphone apps that can replace one or more remote units with sophisticated functionality. However, the basic single-unit remote control still dominates the application. You can even buy general-purpose replacements at your local grocery or convenience store for around $15 and get an exact model-specific replacement for a slightly higher cost via online sources.

Basic IR remote controls use an optical signal and are limited to line-of-sight operation. This is not a concern in most cases and is actually an advantage in many, but it may be a limitation in some situations. For example, garage door openers generally use RF because line-of-sight is not acceptable, but we’ll restrict ourselves to optical units here.

The path to the common IR-based remote control is a tale of engineering development with some twists. The IR units we use today are not just the result of a linear progression to a smaller, better, lighter, and cheaper implementation of the original idea as a result of the usual relentless technical advances and improved manufacturing along a foreseeable route (as has been the case with many other devices and components — think of ICs).

Instead, it is a story of radical shifts in approach and how two unrelated technologies were developed for other applications but were subsequently combined and adapted to meet this longstanding product objective.

This article will look at the history of the standard remote control, emphasizing its use with TV. It will also explore the development that made IR-based one possible today. The story of remote controls is a dual story: the user remote control unit itself and changes in TV-tuner technology that meshed with the unit.

In the 1950s, those earliest days of television, the TV receiver had to tune the 6-MHz-wide VHF channels 2 through 13 with the VHF low band (Band I) between 54 and 88 MHz for channels 2 through 6, and the VHF high band (Band III) between 174 and 216 MHz containing channels 7 through 13. This tuning was accomplished by a mechanical tuner, which used different inductor/capacitor combinations to filter and resonate at the desired channel center frequency in combination with a tube-based oscillator (Figure 3).

Even though there were only a few TV stations on the air, getting up to change channels, adjust the volume, or turn the set on just after you sat down was one of those petty annoyances that apparently needed a solution. That led to the obvious: some sort of remote control was needed, allowing some control over the TV while sitting nearby.

In 1950, Zenith Radio Corp. introduced Lazy Bones, the first commercially successful TV remote control. The idea was obvious enough: a control unit plugged into the TV via a long wire and had two buttons on the top for tuning and volume (Figure 4). This option was priced at $30, roughly equal to $300 today, so it was an expensive add-on.

The corresponding TV tuner assembly had a small motor-like ratcheting assembly that physically rotated the shaft on which the user tuning knob was also located. You could only step in order through the channels and not access them randomly. This was a complicated and costly arrangement, but it worked.

Although Lazy Bones worked, as claimed, the low-voltage wire on the floor between the viewer and the TV was a problem, both in appearance and the risk of people tripping over it (it’s unclear if the tort lawyers were active on this). Zenith knew it had to find a better solution.

Today, Zenith Electronics, LLC is an American research and development company that develops ATSC and digital rights management (DRM) technologies. It is owned by the South Korean company LG Electronics. The fate of competitive powerhouse RCA is similar: RCA is now just a legacy marketing nameplate with no actual products or staff and exists solely to keep the name alive through various marketing deals.]

In 1955, under the technical leadership of Eugene Polley (who also developed the push-button car radio and contributed to video disks), Zenith replaced the wired-connection Lazy Bones with the Flash-Matic (Figure 5). This was a modified incandescent bulb flashlight with a tightly focused directional beam of light used to control a television outfitted with four photocells, one in each corner of the screen.

The light signal would activate one of the four control functions, which turned the picture and sound on or off and turned the channel tuner dial clockwise or counterclockwise. The bottom receptors received the signal to mute and power on/off, and the upper cells received signals to channel up/down.

The light signal was not modulated or encoded for signal integrity, as the technology in a consumer product did not exist (remember, incandescent bulbs have a relatively slow turn-on/turn-off rate). While the Flash-Matic worked in principle, it suffered from inadvertent switching due to sunlight, changes in ambient illumination, and more. It only lasted one year on the market, but it was a precursor to our modern IR-based remote controls in some ways.

With the demise of the Flash-Matic, Zenth sought an entirely different approach to remote control. RF was considered, but with the technology of the time, any sort of remote control would require a large box with vacuum tubes (transistors were just coming into consumer use), a battery, and more, which would be unacceptable. Further, an RF-based unit could cause inadvertent switching of TVs in adjacent apartments depending on the frequency, power, propagation, and physical layout.

That’s why the Zenith team of Polley and engineering genius Robert Adler went in an entirely different physics direction in 1956 with an acoustic-based remote (Adler also developed a greatly improved vacuum tub use of surface acoustic waves for filters). This clever handheld unit had four precision aluminum rods, each tuned to resonate like a tuning fork at a specific ultrasound frequency when struck by a small spring-loaded hammer in the hand-held unit (Figure 6). As with the previous remote controls, functionality was limited to channel up/down and volume up/down.

At the TV, a microphone picked up the ultrasound signals. Then, it filtered them into one of four groups to initiate the desired action, using basic audio-range (non-RF) filtering. No batteries were needed, no interference (walls severely attenuate the ultrasound), and it was limited to mostly line-of-sight behavior — it solved the problem. Yes, dogs were often annoyed by the ultrasonic pings in the 25 to 30 kHz range.

When the user pressed the tuning fork buttons, the unit made a satisfying (or annoying) “click” sound, leading to the term “clicker,” which is still used today as a slang term for the remote control. Although we may think of this as a clunky and inelegant solution, it worked and was widely used from 1956 to 1970. Eventually, as transistors became available, the design was upgraded to use electronics rather than rods to create the ultrasonic signals.

The next part will look at the emergence of our present-day infrared-based remote-control arrangement.

RCA & Color TV: A dominant company and standard, both now gone – Part 1RCA & Color TV: A dominant company and standard, both now gone – Part 2Synthesized tuning, Part 1: Basic frequency-synthesizer principlesSynthesized tuning, Part 2: Advanced synthesizers and performanceRadio receiver architectures, Part 1—TRF and SuperhetRadio receiver architectures, Part 2—Zero-IF and SDRFAQ: What is a Phase Locked Loop (PLL)?

Maximus R&D, “Philips TV Tuner History pt2: 1958-1963 Introduction of UHF and the last valve tuners”The Verge, “The buttons on Zenith’s original ‘clicker’ remote were a mechanical marvel”Zenith, “Six Decades of Channel Surfing”CNET, “Remembering Eugene Polley and his Flash-Matic remote”The Register, “Wireless remote control inventor zaps out at 96”Lemelson-MIT, “Robert Adler: TV Wireless Remote”Historic Tech, “Zenith Lazy Bones- 1st Successful TV Remote Control”DroneBot Workshop, “IR Remotes Revisited – 2023”IEEE Spectrum, “The Day the U.S. TV Industry Died”ME TV, “A history of the TV remote control as told through its advertising”Jasco Products Company, “Universal Remote Code List”Vishay Semiconductors, “Data Formats for IR Remote Control”Circuit Basics, “How to Set Up an IR Remote and Receiver on an Arduino”Autodesk Instructables, “Simple IR Remote Controls”

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