Design of Conventional Information Devices

Toni Ivergard and Brian Hunt

CONTENTS

3.1 Introduction……………………………………………………………………………………………….. 45

3.2 Traditional Information Devices……………………………………………………………….. 47

3.2.1 Different Types of Visual Instruments………………………………………….. 48

3.2.2 Design of Scales and Markings…………………………………………………….. 49

3.2.3 Sound Signals……………………………………………………………………………….. 56

3.3 Visual Display Units (VDUs)………………………………………………………………………. 57

3.3.1 VDU Design…………………………………………………………………………………… 57

3.3.2 Design of Cathode Ray Tubes……………………………………………………… 60

3.3.3 Design of Tables……………………………………………………………………………. 62

3.3.4 Advantages and Disadvantages of VDUs…………………………………….. 63

3.4 Instructions, Forms, Tables, and Codes…………………………………………………….. 67

3.4.1 Diagrams and Tables…………………………………………………………………….. 67

3.4.2 Codes and Symbols………………………………………………………………………. 68

3.4.3 Semantics……………………………………………………………………………………… 68

3.4.4 Grammar……………………………………………………………………………………… 69

3.4.5 Comprehensibility of Codes…………………………………………………………. 70

3.5 Using Colour………………………………………………………………………………………………. 71

3.5.1 Choice of Colours………………………………………………………………………….. 77

3.5.2 Colour Screen Character and Symbol Design………………………………. 77

3.5.3 VDU Screen and Background Requirements……………………………….. 78

3.6 Speech Recognition and Speech Generation……………………………………………… 78

References and Further Reading…………………………………………………………………………. 80

3.1 INTRODUCTION

This chapter describes the design of traditional and conventional information devices, and also the design of devices for communication with computers. The design of instructions, forms, and tables will be dealt with towards the end of the chapter. In Chapter 4 we deal with the latest in design of information devices. A good understand­ing of the ergonomics of analogue information devices provides a firm foundation for a perceptual good design of the modern, more advanced, and flexible information devices. In other words, a good understanding of the design of analogue devices (instruments and controls) will be helpful in the design of the newer, more advanced

displays. Conventional instrumentation can easily be integrated into modern flexible displays using the latest forms of display technology. (See also Chapter 4.)

Also included in this chapter are instructions on how scales and scale markings on visual instruments should be designed, together with the advantages and disad­vantages of different types of visual instruments. It appears, for example, that the common round meter with a moving pointer is best for most applications. Where more exact quantitative readings are necessary and there is plenty of time, the direct – reading digital instrument is best.

The chapter includes a relatively detailed specification for the design of visual display unit (VDU) screens. The main attribute of VDU screens is their flexibility, as they can be used for presenting many different forms of information. However, in control rooms, operators are often required to view and process a large amount of information simultaneously. Therefore it may be necessary to have several VDUs or to have access to other information devices such as overview displays as a comple­ment to VDUs.

This chapter also describes methods for producing diagrams, codes, and sym­bols, and discusses various methods for using colour symbols. The use of colours may have some importance in simplifying the reading of process information. How­ever, the use of colours should be limited, bearing in mind that a significant propor­tion of the population is colour-blind. Colours should be used to supply additional information so that the VDU can be read correctly even if all colour disappears.

In human/machine communication, the human operator receives information via the various information devices. In the control room, the information is either visual or auditory (and may be both), and can be either static or dynamic. For visu­ally-impaired persons these information devices can also be tactile. Dynamic infor­mation is constantly changing, such as the information shown on speedometers, altimeters, radar, TV, temperature, and meters to measure pressure. Static informa­tion does not change over time and includes road markings, maps, notices, manuals, and any printed or written material.

In this chapter we deal primarily with the various types of dynamic information. Static information will also be covered to a certain extent, particularly in Section 3.3 (dealing with VDU screens) and also in Section 3.5. (Chapter 4 deals with the full set of new types of complex displays based on new and emerging technologies.)

Three main types of information devices will be covered in this section:

1. Traditional instruments

2. VDU screens

3. Sound signals

The new generation of VDUs (discussed in Chapter 4) represents—from a tech­nological function—a dramatic paradigm shift in the area of visual displays. How­ever, the functional principles discussed in Chapter 2 are also of relevance for the new generation of displays. The generic principles described in this chapter are of very large importance for a successful use of the new generation of displays. There are many great advantages with the new display technologies; for example, they make it possible for a good overview of the function of the system to be displayed.

This overview is easily lost in the use of cathode ray tube (CRT) and other small – scale display technologies.

Another great advantage of the new technology is its enormous flexibility. How­ever, this also includes an apparent risk. The real strength of the new technology will only be realised if it is combined with the principles discussed in the current chapter. Technological advancement and inherent flexibility make it possible to simulate pre­sentations which characterise the old ‘classic’ instruments. In turn, this makes the new technology more advanced from a functional and perceptual point of view. A classic example is the speedometer of a vehicle. A few decades ago vehicle manu­facturers experimented with speedometers that displayed information in digital and thermometer-like forms. However, ergonomists and human-factor engineers in the automobile and aviation industries could rapidly prove that the superior display style was a traditional speedometer with a clock face and a pointer.

A further advantage is a combination of old analogue and the new digital tech­nologies. This will create redundancy at the same time as it creates trust by the operator. In other words, in the detailed design of the application of the new display technology, we can use our knowledge from the classic display ergonomics.