Ergonomic keyboard design

Abstract

The design of keyboards is still characterized by that of mechanical typewriters. This paper presents a summary of a research project dealing with the ergonomic improvement of keyboards, carried out at the IAO in Stuttgart during the past five years. Extensive laboratory evaluation of experimental keyboards, where different design parameters were tested under real life conditions, have produced a relative optimum regarding ergonomic keyboard design. An accompanying investigation of user acceptance evaluated all realized parameters. In co-operation with a keyboard manufacturer, the results were used to design a marketable product, which may be seen as an important contribution to ergonomic keyboard design.     

Design and evaluation of a curved computer keyboard

Conventional, straight keyboards remain the most popular design among keyboards sold and used with personal computers despite the biomechanical benefits offered by alternative keyboard designs. Some typists indicate that the daunting medical device-like appearance of these alternative ‘ergonomic’ keyboards is the reason for not purchasing an alternative keyboard design. The purpose of this research was to create a new computer keyboard that promoted more neutral postures in the wrist while maintaining the approachability and typing performance of a straight keyboard. The design process created a curved alphanumeric keyboard, designed to reduce ulnar deviation, and a built-in, padded wrist-rest to reduce wrist extension. Typing performance, wrist postures and perceptions of fatigue when using the new curved keyboard were compared to those when using a straight keyboard design. The curved keyboard reduced ulnar deviation by 2.2° ± 0.7 (p < 0.01). Relative to the straight keyboard without a built-in wrist-rest, the prototype curved keyboard with the built-in padded wrist-rest reduced wrist extension by 6.3° ± 1.2 (p < 0.01). There were no differences in typing speed or accuracy between keyboards. Perceived fatigue ratings were significantly lower in the hands, forearms and shoulders with the curved keyboard. The new curved keyboard achieved its design goal of reducing discomfort and promoting more neutral wrist postures while not compromising users' preferences and typing performance.     

Visual and manual loadings with QWERTY-like ambiguous keyboards: Relevance of letter-key assignments on mobile phones

Mobile phone touchscreens have many ergonomic problems related to text entry. Previous studies, which attempted to use ambiguous keyboards to resolve problem of small keys, focused on the disambiguation process without consideration of the user loading on graphic user interface. This study investigates user loadings, which interfere with performance in the key selection phase when using an ambiguous keyboard. Hence, three QWERTY-like ambiguous keyboards and a standard QWERTY keyboard were compared via visual search and manual operation experiments. The visual search experiment shows that layouts with many letters per key were strongly related to long visual search times, and layouts with large keys were operated faster and more accurately in the manual operation experiment. Consequently, the trade-off between visual and manual loading differed among different letter-key assignments. This study is important in that it elucidates the impacts of visual and manual loadings on ambiguous keyboards, as well as in providing user interface designers with an enhanced understanding of how to design ambiguous keyboards based on user criteria.Relevance to industryAmbiguous keyboard designs in previous studies were generally far from the actual needs of users. This study examines the factors affecting text entry performance of users via the user-centered approach, improving the understanding of designers.     

Design and evaluation of small,linear QWERTY keyboards

Miniature keyboard design is motivated by the need for smaller mobile devices with maximum user display area. Thus, this study developed four miniature keyboard designs which varied from conventional keyboard design in terms of their configuration and layout. The purpose of this study was to evaluate the input speed, accuracy, comfort, likability and learnability of four miniature keyboards. Sixteen fast typists and 16 slow typists were recruited to use these four miniature keyboards. The results showed that the rectangular-shaped keycaps of 3 letters with separated keycaps of numerals obtained the best proficiency speed, highest comfort and greatest user acceptance among the four keyboards. Moreover, the keyboards with square-shaped keycaps had better input accuracy compared to rectangular-shaped keycaps. Finally, the proposed keyboards were smaller than current keyboards, and the performance for all of the small keyboards was worse than that of the conventional keyboard.     

Design of an alternative keyboard layout for the Greek language

This study constitutes a first attempt to design an alternative keyboard layout for the Greek language that satisfies ergonomic requirements. The criticisms leveled at the standard keyboard layout, the opportunities offered by recent changes in the technology of editing devices, and the increasing number of new keyboard users are among the reasons justifying this study. Ten ergonomie requirements were considered during the design process. The designed keyboard layout was compared to the standard Greek keyboard by two different evaluations. The first evaluation, which was analytical, was based on the ergonomie requirements and the frequencies of letters and digrams in the Greek language. The second evaluation, which was experimental, was aimed at comparing the typing performance as well as the ease of learning of the two keyboard layouts. The results showed that: (1) the designed keyboard layout satisfies the ergonomie requirements much better, and (2) there were no significant differences in the typing performance between the two keyboards, for equal typing training and for small typing periods. It is concluded that the improved layout could be used as a programmed alternative alongside the standard keyboard.     

Cyber Swarm optimization for general keyboard arrangement problem

Traditional QWERTY keyboard has been known to be an ill design due to its low typing speed, fatigue-inducement, no reference to learnability, to name a few. Many researchers have put their effort on optimizing the character arrangement of the keyboard by taking into account the co-occurrence frequency of characters in words, typing ergonomics, and word disambiguation effectiveness. However, most of the existing works addressed the problem for a single objective instead of multiple ones, and the design of customized keyboards for motor-impaired users is often overlooked. In this paper, we propose a general mathematical model that integrates varying keyboard arrangement context. A Cyber Swarm method considering multiple objectives is proposed and it can create additional benefits that cannot be obtained by traditional methods. Our Cyber Swarm method accommodates ergonomic criteria and disambiguation/prediction effectiveness simultaneously. Experimental results manifest that the Cyber Swarm keyboard outperforms several benchmark keyboards and other competing algorithms. We also show an illustrative example for preliminary keyboard shape design which could be very useful in customized keyboard production for motor-impaired users whose physical capacity has been evaluated a priori. Finally, an empirical experiment involving human subjects is performed in order to analyze the feedbacks from humans’ experiences in using the new keyboard layouts.

Relevance to industry

Using the proposed general framework for keyboard arrangement, various scenarios (for example, single-character or multi-character keys, single-finger or multi-finger typing) raised in industrial production can be all taken into account without the hassle to change solution methods for different settings. Hence, the time and costs in industrial production for customized keyboard is significantly reduced.     

An evaluation of the ergonomics of three computer keyboards

The influence of keyboard design on hand position, typing productivity and keyboard preference was evaluated by comparing two segmented alternative designs with the linear standard keyboard. The FIXED alternative keyboard featured a split angle of 12 degrees and a moderate lateral inclination angle of 10 degrees. The adjustable OPEN alternative keyboard was used with a 15 degrees split setting, which resulted in a marked 42 degrees of demiboard lateral inclination. Sixteen typists, who completed 10 h of training on both alternative keyboards, were videotaped while typing set texts on all three keyboards. Forearm and wrist angles based on three-dimensional video analyses were significantly different (p<0.05) among the three designs tested. Both alternative keyboards placed the forearm and wrist closer to neutral positions than did the standard keyboard. While the OPEN keyboard reduced pronation, it simultaneously increased radial deviation. The FIXED keyboard kept the forearm in moderate pronation and the wrist closer to neutral. More time was spent in neutral and moderate ranges of wrist motion when subjects typed on the FIXED compared with the other two designs. With respect to the standard keyboard, typing productivity was reduced by 10% on the FIXED and 20% on the OPEN designs. No significant difference in preference was found between the standard and FIXED keyboards, both of which were preferred over the OPEN. It was concluded that, of the three keyboards evaluated, the FIXED design incorporated moderate changes to the standard keyboard. These changes promoted a more natural hand position while typing thereby reducing the potential for cumulative trauma disorders of the wrist. In addition, the FIXED design preserved a reasonable level of productivity and was well accepted by users.     

Keyboards and keying An annotated bibliography of the literature from 1878 to 1999

This bibliography covers the period from 1878 through 1999. It contains, in chronological order, a thorough sampling of the literature concerning the design and use of keyboards. The sources are selected and annotated to reflect the status of engineering and technology know-how, and knowledge about ergonomic aspects of the use of the keyboards with, first, mechanical typewriters, then electric typewriters and finally, from the 1960s on, computers. The bibliography illustrates the origin of Sholes’ 1878 QWERTY keyboard and its continued use in spite of its many shortcomings, which may be – at least partially – the reason for cumulative trauma disorders in yesteryear’s typists and today’s keyboarders. Published online: 6 September 2001     

Acceptance of the adjustable keyboard

The acceptance of a split keyboard with a user-adjustable angle (adjustable keyboard) and its impact on postural discomfort and general comfort of users was tested in a comparative laboratory experiment with 26 typists as subjects. The comparison was made with a standard keyboard. The results were interpreted using the findings of an earlier field study with another split keyboard with a fixed angle between the halves of the device. Both split keyboards improved postural comfort; however, the period of familiarization was much longer with the fixed-angle split keyboard. Since the adjustable keyboard allows a change, in the angle from 0 to 30^°, a person's posture can be adopted on a step-by-step basis. Thus, the new adjustable design has much better prospects of being accepted in practice than former attempts where the value was more academic than practical. The analysis of throughput and errors, under self-determined angles of the test object and with an angle comparable with those of fixed-angle split keyboards, reveals that users in work situations are not likely to accept fixed-angle split keyboards (30°) since throughput is substantially reduced during the long period of familiarization, accompanied by a substantial increase in errors. The results of this study confirm the assumption that new adjustable split keyboard design, once accepted by the users, may improve postural comfort, general comfort, and reduce fatigue. These effects could be demonstrated both in a short-term experiment and a long-term field study. The basic design feature of the adjustable keyboard, adjustability, is in agreement with the conclusions of recent studies on the introduction of ergonomically designed keyboards.     

A review of: “Applying Psychology: Understanding People” By R. C. Beck (New Jersey: Prentice Hall, 1982.) [Pp.484.] $15-70. ISBN 0-13-043463-9.

This study investigated how ergonomic design influences neck-and-shoulder muscle strain, through keyboard assessment. Muscular activity was measured electromyographically (EMG) from six muscles in the forearm and shoulders of eight experienced typists using each of five different types of keyboard: one mechanical, one electromechanical, and one electronic typewriter; one personal computer/word processor (PC-XT) keyboard; and one angled at 20° in the horizontal plane. The impact on muscular activity of using a palmrest was also studied. The mechanical typewriter induced a higher strain in the forearm and finger muscles than did the modern typewriters and keyboards. These induced no different strain on the neck-and-shoulder muscles, except for the right shoulder muscle, which was more active with the electronic typewriter than with the other machines. Using a palmrest did not decrease the strain on the muscles investigated. Use of the ‘angled’ PC-XT keyboard did not influence the measured muscular load on the forearm and finger muscles compared to typing on an ordinary PC-XT keyboard, but decreased the extensor muscular strain compared to the electronic typewriter.     

Building and testing optimized keyboards for specific text entry

OBJECTIVE: We explore how to optimally design systems for information input. BACKGROUND: As computers are introduced into ever more devices with new methods of inputting information, there is a need for specialized systems that are optimally designed for their particular use. METHOD: The study demonstrates how to use a model of text entry times to build optimized keyboards for specific sets of text. The technique is demonstrated by using Fitts' law to model text entry times. Alphabet letters are assigned to keys in a way that minimizes predicted entry time for the specified set of text. The predicted entry times are validated by an experiment in which two keyboards are optimized for different sets of text. RESULTS: Text entry is faster for the keyboard optimized for that text compared with the keyboard optimized for the other text. Learning to use the keyboards is fairly quick, with significant learning being observed after only one half-hour session. CONCLUSION: There is a need and an ability to design specialized keyboards for some situations. The study demonstrates that optimization of keyboards can decrease text entry times. APPLICATION: This research shows how to design optimized keyboards for many different situations. The approach should be useful for aviation, medical, industrial, and other specialized situations in which normal keyboard designs cannot be used.     

The split keyboard: an ergonomics success story

OBJECTIVE: The author reviews the paper by Kroemer (1972) on the design of the split geometry keyboard and the subsequent 35 years of research on the topic. BACKGROUND: It was first suggested in the 1920s that arm strain in the typist could be reduced by splitting the keyboard into two halves and inclining the two halves laterally. The first systematic research on the split keyboard was conducted by Kroemer in the 1960s and published in his 1972 article. METHODS: The literature on split geometry keyboards was identified, and the progression of the research was reviewed. RESULTS: The Kroemer article marked the beginning of a prolonged, worldwide research effort to determine whether and how the split keyboard design might improve comfort and prevent pain in keyboard users. CONCLUSIONS: In the early 1990s, split keyboard designs began to be broadly commercially available. Clear evidence of a health benefit of the split keyboards emerged in the late 1990s. By 2006, a split keyboard was the number one-selling keyboard, of all keyboards sold, in the U.S. retail market. APPLICATION: The history of research on this topic, the challenges to changing the conventional design, and the broader acceptance of the split design are a success story with lessons for all of us.     

Keyboard entry

Many recent studies of keyboard entry are summarized with particular emphasis on performance data and fundamental questions about the design of keyboards. The role of auditory and visual feedback and physiological measurements are reviewed. Typical speed and error rates are given for several types of situations and operators. Other methods of data entry are considered, as are source documents, ordering of keys, keyboard interlocks, and chord keyboards. These data should be of interest to anyone concerned with the design and use of keyboards or other data entry devices.     

The effect of six keyboard designs on wrist and forearm postures

There is increasing evidence that alternative geometry keyboards may prevent or reduce arm pain or disorders, and presumably the mechanism is by reducing awkward arm postures. However, the effect of alternative keyboards, especially the new designs, on wrist and arm postures are not well known. In this laboratory study, the wrist and forearm postures of 100 subjects were measured with a motion analysis system while they typed on 6 different keyboard configurations. There were significant differences in wrist extension, ulnar deviation, and forearm pronation between keyboards. When considering all 6 wrists and forearm postures together, the keyboard with an opening angle of 12 degrees , a gable angle of 14 degrees , and a slope of 0 degrees appears to provide the most neutral posture among the keyboards tested. Subjects most preferred this keyboard or a similar keyboard with a gable angle of 8 degrees and they least preferred the keyboard on a conventional laptop computer. These findings may assist in recommendations regarding the selection of keyboards for computer usage.     

嵌入式SoC中键盘控制器的设计与实现

“龙腾”S1是以工业控制应用为背景的高性能嵌入式SoC，键盘控制器为其整个键盘系统提供硬件基础。本文详细分析了键盘系统的工作机制，给出了一种键盘控制器的设计结构和控制时序，通过优化某些具体电路增加设计的可重用性和可验证性。最后经过FPGA验证，证明该设计完全支持通用的PS／2键盘，在时序和功能上满足了设计要求。     

Muscular loading and subjective ratings of muscular tension by novices when typing with standard and split‐design computer keyboards

The objective of this research project was to compare two different computer keyboard designs with respect to their effect on the extent of muscular loading in the right and left trapezius and extensor muscles during typing. The two computer keyboards used in this study were (1) a classic or standard keyboard, and (2) a split‐design keyboard. Evaluation of muscular loading was done using the electromyography (EMG) technique and subjective ratings of muscular tension. Sixteen women, between 18 and 26 years of age, with similar secretarial experience and limited typing abilities, took voluntary part in the experiment. Each subject used both keyboards for 15 min. The EMG signals recorded during typing sessions were those of the left and right sides of trapezius (m. trapezius pars descendeus) and extensor (m. extensor carpi radialis brevis et longus) muscles. Upon completion of each task, subjects were asked to evaluate perceived levels of muscular tension in the shoulder‐neck area and forearms. The results showed that the split‐design computer keyboard significantly reduces muscular loading of the trapezius muscle and subjective feelings of muscular tension in the shoulder‐neck area.     

Investigating touchscreen typing: the effect of keyboard size on typing speed

Two studies investigated the effect keyboard size has on typing speed and error rates for touchscreen keyboards using the lift-off strategy. A cursor appeared when users touched the screen and a key was selected when they lifted their finger from the screen. Four keyboard sizes were investigated ranging from 24.6 cm to 6.8 cm wide. Results indicate that novices can type approximately 10 words per minute (WPM) on the smallest keyboard and 20 WPM on the largest. Experienced users improved to 21 WPM on the smallest keyboard and 32 WPM on the largest. These results indicate that, although slower, small touchscreen keyboards can be used for limited data entry when the presence of a regular keyboard is not practical. Applications include portable pocket-sized or palmtop computers, messaging systems, and personal information resources. Results also suggest the increased importance of experience on these smaller keyboards. Research directions are suggested.     

Chord keyboards

Unlike the standard typewriter keyboard, keying on a chord keyboard is carried out by simultaneous patterned pressing of one or more keys. This results in fewer keys being needed on a chord keyboard when compared with a sequential keyboard, where keys are pressed one at a time. For example, five keys allow a total of 31 (2(5) - 1) different chord combinations to be generated. The feasibility of using a chord keyboard as a data entry input device was first seriously investigated in the mid-1950s by the Canadian Post Office. The trend towards research into chord keying reached a peak around 1960 when International Business Machines (IBM) studied two chord keyboards to rival the typewriter. It was not until the 1970s that chord keyboards became commercially available and within the last decade three chord keying devices have been marketed. The emphasis on the development of these recent keyboards has moved from task specific to more general purpose applications. This paper (based upon Martin (1980) the author's maiden name) reviews the chord keyboards which have been developed since the 1940s with special emphasis on the mail sorting application, and draws some conclusions concerning future developments.     

Product development of an ergonomic keyboard

Abstract

The first truly ‘ergonomic’ keyboard for modern VDUs was shown to the public in April 1983 in Zurich. This split keyboard was the result of a research programme carried out by the Department of Hygiene and Work Physiology, ETH, Zurich. The ergonomic factors of the keyboard were convincing to the press, computer manufacturers and users. The steps from models of this keyboard to the final product and related problems of industrial design and engineering are explained. This will help in understanding the distinctive time lags between the results of scientific research and the availability of a product in the market–place.     

Wrist and forearm posture from typing on split and vertically inclined computer keyboards

A study was conducted on 90 experienced office workers to determine how commercially available alternative computer keyboards affected wrist and forearm posture. The alternative keyboards tested had the QWERTY layout of keys and were of three designs: split fixed angle, split adjustable angle, and vertically inclined (tilted or tented). When set up correctly, commercially available split keyboards reduced mean ulnar deviation of the right and left wrists from 12 degrees to within 5 degrees of a neutral position compared with a conventional keyboard. The finding that split keyboards place the wrist closer to a neutral posture in the radial/ulnar plane substantially reduces one occupational risk factor of work-related musculoskeletal disorders (WMSDs): ulnar deviation of the wrist. Applications of this research include commercially available computer keyboard designs that typists can use and ergonomists can recommend to their clients in order to minimize wrist ulnar deviation from typing.