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Using Ergonomics to Design the Butterfly Keyboard

By Brian Hackett

Eighteen months ago, a team at Connectrix set out with the task of developing a compact and comfortable keyboard for use with Connectrix and other companies' PDAs. It was a difficult project, partially because of its requirements on the durability and reliability of the keyboard, but also because of the many considerations regarding the keyboard's ease of use. The team turned to ergonomics, a field of study concerned with how people use machines, and, more importantly, how to improve the machines based on the problems people have with using them.

Ergonomics is a focused science which draws heavily from many disparate fields. One aspect focuses on psychology, on examining peoples' conceptions of machines, so as to understand their intuition about how things should behave. Another important aspect is concerned with how people actually interact with machines. Anthropometry is the study of peoples' physical features, the shape of their hands or body, and is used to design machines that will fit their users, as opposed to machines which require their users to fit them. Anthropometry has played a very important role in the development of computer peripherals and devices, including PDAs. A particularly interesting case is the keyboard, which, despite its central role to human-computer interaction, has only recently come under the lens.

Historically, keyboards have strayed very little from the typewriters which came before them. Ergonomics as a science was not developed until after the second World War, meaning that human factors played a very small role when Christopher Sholes developed the original typewriter in 1873. Instead, mechanical issues were the main concern. We still use the same basic key design, which was chosen to easily facilitate the actions of the bars which swing up to print individual letters. A more egregrious holdover is that of the earliest typewriter's key layout. The 'QWERTY' arrangement was designed to be inconvenient: if two adjacent letters on the keyboard were typed right after another, the typewriter would frequently jam. Putting common pairs of letters far away on the keyboard has the effect of slowing down typists, since common letters are harder to reach. Since then, ergonomic and linguistic principles have never won out over the desire to maintain a constant layout, and keyboards today use the same 'QWERTY' arrangement.

Ergonomics has played an important role in recent improvements to keyboards, however, on both anthropometric and psychological grounds. Anthropometric methods were used to improve the shape of keyboards, giving us a wide variety of 'ergonomic' keyboards. These have usually taken the shape of keyboards with wrist supports or keyboards broken in half, oriented to reduce wrist and hand fatigue. Psychological studies of peoples' interactions with computers have given us new buttons on the top of many keyboards, which allow easy access to the computer's most commonly used features.

Both of these advancements were taken into consideration by the Connectrix team. While a full-sized, ergonomic keyboard is not something that can be folded up and put into a pocket, hinges have been added which allow the keyboard to be tilted at several angles, improving writing speed and comfort levels. As with other modern keyboards, small buttons have been added which open up the common applications found on Connectrix PDAs.

A third ergonomics concern emerged in development of the Butterfly keyboard. Although there is no longer a mechanical motivation behind it, modern keyboards still use the same key-based design for typing in letters. What the Connectrix team found is that people need tactile feedback from the keyboard as they're typing. A touchpad would be very simple to make and use, but since there is no physical indication to the typist that a key has been pressed, more errors result. Full-sized keys are infeasible for a collapsible keyboard, since it must fold up to become as compact as possible. The team solved this dilemma by using a different type of key. A carefully designed rubber covering for the board allows a smaller profile, but still gives an appropriate amount of resistance when keys are pressed. By carefully studying the cues people take in when they write using a keyboard, ergonomics has enabled Connectrix to develop a durable, foldable keyboard that feels just as right and natural as a regular keyboard.

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