Data entry devices
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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:

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Presentation Transcript
Data entry devices l.jpg
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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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