data entry devices n.
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Data Entry Devices

Data Entry Devices

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Data Entry Devices

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  1. Data Entry Devices • Introduction • Keyboard entry devices are superior to other devices such as knobs, levers, and thumb wheels. • Speed and accuracy are dependent on the quality of data given to the operator, based on the following criteria: • Messages of the 10 numbers presented in random order are not entered more rapidly than those of the full 26 letters • The operator is familiar with the format of the information to be entered • Upper- and lowercase characters are used for written text • Long messages or strings of digits are entered as chunks

  2. Keyboards • Chord versus Sequential Keyboards • Chord keyboards require activation of one or more keys simultaneously (stenotype machines or pianos) • Sequential keyboards are the standard type, where there is a specific key for for each character • Chord keyboards are very good for one-handed data entry • Chord keyboards are much harder to learn, but tend to be faster. • There is no particular need for general-purpose chord keyboards, as sequential keyboards fulfill most requirements • For special situations, chord keyboards can be superior

  3. Keyboards • Alphabetic Keyboards • QWERTY keyboards were designed to slow the typing process • The best alternative was the Dvorak keyboard (Figure 11-19) • QWERTY is entrenched in our present society, and is unlikely to change • Numeric Keyboards • There are two primary numeric keypads in use today: • The only differences between the two is for occasional users, who will do better with the telephone layout • Calculator Layout • Telephone Layout

  4. Keyboards • Keyboard feel is a combination of a number of characteristics: • The feel is often mentioned in product review articles • Three keyboards were compared (Table 11–4) • The linear-spring keyboard was the least preferred • The elastomer keyboards had the fastest times and a low error rate (Figure 11-20) • Key travel • Resistance characteristics • Auditory activation feedback • Hysteresis

  5. Keyboards • Membrane Keypads • Used in the consumer market, in microwaves, for example • Consist of contacts separated by a thin non-conductive layer • Key travel is virtually nonexistent • To reduce accidental activation, often more force is required • The contact areas are often difficult to locate • With practice, the keypads become easier to use • Three feedback procedures were used to aid the user: • Auditory tone, for activation • Embossing, for finger-position • Snap domes, to provide both forms of feedback

  6. Keyboards • Split and tilted keyboards • Normal keyboards require the hands bend outward (Figure 11-22) • This can lead to tenosynovitis and eventually CTS • People become accustomed to the designs quickly, and prefer them • Handwritten and Gestural Data Entry • The technology has become possible for computers to translate handwriting into computer text • At present, it is slow and more error-prone • Gestural inputs have been used for text-editing tasks • Figure 11- 24 • When successfully implemented, gestural inputs are faster than those with a keyboard

  7. Cursor Positioning Devices • Introduction • Widespread computer use has made these devices necessary • Touch Screen • Use a screen overlay which is interrupted when the screen is touched • Easy to learn, but not very accurate • Parallax becomes a problem, reducing the effectiveness of the pad • Figure 11-25 defines good pad sizes

  8. Cursor Positioning Devices • Light Pen • The pen is pressed on the screen, and reads the CRT scanning beam • Pointing resolution is better than with the touch screen

  9. Cursor Positioning Devices • Graphics Tablet • Position of tablet reduces arm fatigue over a touch screen • Digitizing Tablets offer the benefits of a light pen without the fatigue problem • Two types of positioning: • Absolute positioning is faster and more accurate with a small gain • Figure 11-26 shows this relationship • A lead-lag compensation system gives better speeds with only slightly higher error rates • Relative positioning • Absolute positioning

  10. Cursor Positioning Devices • Mouse • A mouse is easy and fast to use, and it is a relative positioning system • A clear space near the computer is required to operate it • Other Cursor Positioning Devices • Keyboards • Joysticks • Trackballs

  11. Cursor Positioning Devices • Comparison of Cursor Positioning Devices • There is a tradeoff between accuracy and speed (Table 11-5) • The selection of the best device must take into account the relative importance between speed and accuracy • The mouse was found to be the fastest and most accurate in a text-editing task • In another task, the mouse and trackball were found to be the best • Such features as C/R ratio, physical size, and feedback have not yet been systematically investigated

  12. Special Control Devices • Introduction • New devices are replacing standard control devices • Teleoperators • Teleoperators are remotely controlled devices that augment the physical skills of the operator • Today they are used for handling dangerous materials or working in hostile environments • Human Factors considerations • Lack of physical feedback • Deny visual access • Often lack binocular vision • Time delays for large separations • Design of controls for complex effector

  13. Special Control Devices • Speech-Activated Control • Advantages: • Applications for Speech Recognition: • Operator not tied to console • Hands are free • Data entry occurs simultaneously with other tasks • Operator moves around while entering data • Well suited for use by the handicapped

  14. Special Control Devices • Types of Speech Recognition Systems • Speaker independent systems are classed as follows: • These systems are limited, with small vocabularies • Speaker dependent • Speaker independent • isolated-word • connected-word • continuous-speech

  15. Special Control Devices • Speaker dependent, isolated-word systems • Performance of Speech Recognition Systems • Performance of a good system is as good or better than keyboard data entry, although error rates may be higher • 20 to 200 word vocabularies • Maximally discriminable vocabularies have a great advantage • Each word must be set off with pauses (training required) • Systems require 4 repetitions of each word to generate an accurate vocabulary

  16. Special Control Devices • Eye-Activated Control • To date, most eye-control applications have been in the military • A helmet is used to track eye movements, and a voice activation is used to actuate the command • Accuracy of eye positioning has been found to be ±10 min of Visual Angle in the center of the visual field

  17. Special Control Devices • Disadvantages of eye control: • Overburdening of the visual system • Control is difficult in a vibrating or accelerating environment • Visual distractions can degrade performance • Median total activation times of 1.5 to 1.7 seconds • Delays inherent in the speech recognition system result in slower times when voice is used to accept the eye-controlled selection