It's hard to believe that just a few decades ago, touchscreen technology could only be found in science fiction books and film. These days, it's almost unfathomable how we once got through our daily tasks without a trusty tablet or smartphone nearby, but it doesn't stop there. Touchscreens really are everywhere. Homes, cars, restaurants, stores, planes, wherever—they fill our lives in spaces public and private.
It took generations and several major technological advancements for touchscreens to achieve this kind of presence. Although the underlying technology behind touchscreens can be traced back to the 1940s, there's plenty of evidence that suggests touchscreens weren't feasible until at least 1965. Popular science fiction television shows like Star Trek didn't even refer to the technology until Star Trek: The Next Generation debuted in 1987, almost two decades after touchscreen technology was even deemed possible. But their inclusion in the series paralleled the advancements in the technology world, and by the late 1980s, touchscreens finally appeared to be realistic enough that consumers could actually employ the technology into their own homes.
This article is the first of a three-part series on touchscreen technology's journey to fact from fiction. The first three decades of touch are important to reflect upon in order to really appreciate the multitouch technology we're so used to having today. Today, we'll look at when these technologies first arose and who introduced them, plus we'll discuss several other pioneers who played a big role in advancing touch. Future entries in this series will study how the changes in touch displays led to essential devices for our lives today and where the technology might take us in the future. But first, let's put finger to screen and travel to the 1960s.
1960s: The first touchscreen
Historians generally consider the first finger-driven touchscreen to have been invented by E.A. Johnson in 1965 at the Royal Radar Establishment in Malvern, United Kingdom. Johnson originally described his work in an article entitled "Touch display—a novel input/output device for computers" published in Electronics Letters. The piece featured a diagram describing a type of touchscreen mechanism that many smartphones use today—what we now know as capacitive touch. Two years later, Johnson further expounded on the technology with photographs and diagrams in "Touch Displays: A Programmed Man-Machine Interface," published in Ergonomics in 1967.
A capacitive touchscreen panel uses an insulator, like glass, that is coated with a transparent conductor such as indium tin oxide (ITO). The "conductive" part is usually a human finger, which makes for a fine electrical conductor. Johnson's initial technology could only process one touch at a time, and what we'd describe today as "multitouch" was still somewhat a ways away. The invention was also binary in its interpretation of touch—the interface registered contact or it didn't register contact. Pressure sensitivity would arrive much later.
Even without the extra features, the early touch interface idea had some takers. Johnson's discovery was eventually adopted by air traffic controllers in the UK and remained in use until the late 1990s.
1970s: Resistive touchscreens are invented
Although capacitive touchscreens were designed first, they were eclipsed in the early years of touch by resistive touchscreens. American inventor Dr. G. Samuel Hurst developed resistive touchscreens almost accidentally. The Berea College Magazine for alumni described it like this:
To study atomic physics the research team used an overworked Van de Graff accelerator that was only available at night. Tedious analyses slowed their research. Sam thought of a way to solve that problem. He, Parks, and Thurman Stewart, another doctoral student, used electrically conductive paper to read a pair of x- and y- coordinates. That idea led to the first touch screen for a computer. With this prototype, his students could compute in a few hours what otherwise had taken days to accomplish.
Hurst and the research team had been working at the University of Kentucky. The university tried to file a patent on his behalf to protect this accidental invention from duplication, but its scientific origins made it seem like it wasn't that applicable outside the laboratory.
Hurst, however, had other ideas. "I thought it might be useful for other things," he said in the article. In 1970, after he returned to work at the Oak Ridge National Laboratory (ORNL), Hurst began an after-hours experiment. In his basement, Hurst and nine friends from various other areas of expertise set out to refine what had been accidentally invented. The group called its fledgling venture "Elographics," and the team discovered that a touchscreen on a computer monitor made for an excellent method of interaction. All the screen needed was a conductive cover sheet to make contact with the sheet that contained the X- and Y-axis. Pressure on the cover sheet allowed voltage to flow between the X wires and the Y wires, which could be measured to indicate coordinates. This discovery helped found what we today refer to as resistive touch technology (because it responds purely to pressure rather than electrical conductivity, working with both a stylus and a finger).
As a class of technology, resistive touchscreens tend to be very affordable to produce. Most devices and machines using this touch technology can be found in restaurants, factories, and hospitals because they are durable enough for these environments. Smartphone manufacturers have also used resistive touchscreens in the past, though their presence in the mobile space today tends to be confined to lower-end phones.
Elographics didn't confine itself just to resistive touch, though. The group eventually patented the first curved glass touch interface. The patent was titled "electrical sensor of plane coordinates" and it provided details on "an inexpensive electrical sensor of plane coordinates" that employed "juxtaposed sheets of conducting material having electrical equipotential lines." After this invention, Elographics was sold to "good folks in California" and became EloTouch Systems.
By 1971, a number of different touch-capable machines had been introduced, though none were pressure sensitive. One of the most widely used touch-capable devices at the time was the University of Illinois's PLATO IV terminal—one of the first generalized computer assisted instruction systems. The PLATO IV eschewed capacitive or resistive touch in favor of an infrared system (we'll explain shortly). PLATO IV was the first touchscreen computer to be used in a classroom that allowed students to touch the screen to answer questions.