Did you know that the membrane switch, which can be found in a wide variety of modern devices, is the result of a development process that’s lasted for nearly five decades? Over the years, this technology has significantly influenced human-machine interface design by bridging the gap between form and function.
1970 – The first steps towards innovation
The very first iterations of the membrane switch were actually screen-printed graphic overlays. Their sole purpose was to improve the appearance of the mechanical keyboards underneath them.
It was only in the early 1970’s that the first keypads made with electronic circuits using copper- or silver-infused ink were introduced to the market. These products were comprised of two conductive layers and one spacer, and made of polycarbonate.
The use of these keypads was limited to electronic products intended for the general public, like calculators or household appliances. They were therefore considered to be an inexpensive yet unreliable way to input data. While these membrane keyboards were more modern and aesthetically pleasing than mechanical keyboards, they were difficult to use. They did not provide tactile feedback, and mistakes were common. They were not very durable, either: over time, the polycarbonate began to break down and cracks began to form around the keys.
Towards the end of the 1970’s, these problems were solved with the introduction of metallic domes and polyester as a base material. Now far more durable and easier to use, membrane switches set their sights on a new market: personal computers. Between 1979 and 1981, three popular models incorporated this technology: the Sinclair ZX80 and ZX81, and the Atari 400.
1980 – A new era
Bringing QWERTY membrane keyboards to market presented a challenge: to convince thousands of typists to adopt this new technology. These professionals, who were trained to enter text using the kind of mechanical keyboard you find on a typewriter, struggled to give up this familiar tactile experience. One article, published in the New York Times in 1981, describes the stalemate very well. The author explains that manufacturers needed to “take their modern technology and make it old-fashioned.”
The introduction of IBM’s model M mechanical keyboard in 1984 officially marked the end of the membrane switch within the emerging personal computer market for almost a decade. In the early 1990’s, it was Apple that finally resolved the dilemma the Times had written about: using membrane switch technology, Apple’s new product included thin keys that mirrored the feel of a mechanical keyboard. Lighter, smaller, and quieter, this hybrid gave way to the computer keyboard style we know today.
Having proven its exceptional durability during the 80’s, the traditional membrane switch dethroned the mechanical keyboard in a number of industries. For example, the medical, food, and manufacturing markets adopted this technology en masse. These interfaces, which are sealed and produced using strong polymers, are able to withstand extreme conditions: contact with chemical substances, water, dust, or corrosive cleaners has no effect on their performance.
Over the course of the next few decades, a number of innovations made the membrane switch an even more desirable product. It has become increasingly compact, and can be integrated into products without constraints. Its flexibility and slim profile also allow for it to be installed on a curved surface. The advent of LED and more sophisticated optical fibers further advanced the design possibilities, all while facilitating the use of these interfaces.
Perfecting this new technology catalyzed the expansion of the membrane switch family, bringing capacitive interfaces into the mix. Designed without moving pieces, these keyboards open the door to even more design freedom while offering enhanced durability.
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Despite its rocky start, the membrane switch played an integral role in the development of human-machine interfaces (HMI): it helped improve the user experience, while elevating products to new aesthetic heights. Even today, this technology still has lots of room for imagination and innovation.
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