Book revietus

Technological developments in displays

'Advances in display techno- logy IV', Edited by E. Schlam, SPIE Proceedings, Volume 457, 1984 pp vi + pp 122, $47

A conventional book allows the author to establish a start-point of knowledge which the readers are assumed to have, and then develop his selected themes from there. This book is the proceedings of a con- ference (held in Jannary 1984) by the American Society of Photo-Opti- cal Instrumentation Engineers (SPIE). As with any proceedings it reproduces t.he papers as pre- sented by thek authors, with the result that there is no real cohesive theme and that the reader is left with the sort of questions in his mind that get asked and answered in the discussion that is an integral part of any conference. It is a pity that post- conference sales of proceedings cannot contain a precis of question time.

Of the 21 papers, a third are sub- stantially tutorial in nature. Papers on ergonomic standards, screen glare, colour deficiency, high resol- ution electron-optics and TV inter- lacing each provide structured treatments of their subject and do not require detailed prior know- ledge, but which, by the same token, contribute nothing to the knowledge of the expert in the field. The papers on ergonomics and glare provide an awareness of these issues in the context of VDUs with an outline of problems and sol- utions. Additionally, the ergonomics paper seeks to brief the American reader with the progress of stan- dards in Europe. An overview of the three types of colour-vision defi- ciency leads to a brief considera- tion of the relevance to colour dis- plays, and a set of guidelines. Set in the context of a proprietary pro-

duct, the paper on electron optics gives a comprehensive description in qualitative terms of the various elements of a focus and deflection system, and their adjustment.

Two papers consider the sizes and data densities needed for dis- plays for the electronic office and translate these into raster scan rates and video bandwidths, without really justifying the targets set.

Five papers describing pro- ducts or product applications also contain useful tutorial or educative material. These encompass colour polarizers, outlining the improved environmental survivability of dic- hroic dyes relative to iodine; colour- vision spatial resolution (in a paper whose ra/son d'~me is to propose the use of the colour LCD shutter with a white CRT to generate col- outed images); laser beam printers, discussing the design factors of using a dual-beam configuration to reduce the size of the equipment; and electroluminescence (EL), in the context of a large-panel product but giving varidus basic data on the performance of the Zr~ phosphor and detailing a revised scanning arrangement claimed to reduce power consumption. Two papers are devoted to a gas-electron-phos- phor fiat-panel display describing in some detail its construction and scanning mechanism.

Two papers describe new work in perception with a scheme

to present a depth component to TV by switching between left and right- eye images (or even more novel, two images vertically displaced) without using synchronized shutters in front of the eyes; and the use of holography to superimpose move- able images in the field of view of a driver undergoing training on the open road.

Two papers describe new technology developments in the EL field. An implementation of the much awaited black layer is described claiming that placing the layer between the insulant and the aluminium electrode gives improved electrical characteristics. Brightness and contrast ratios com- patible with daylight viewing are reported. The other paper discus- ses very large EL panels and, among other factors, derives requirements for the necessary conductor resist~'ty. A novel com- pound electrode is described in which the familiar ITO is supplemented by an alurninium stripe.

A paper on the first commer- cial CdSe thin-film-addressed LCD is disappointingly brief. A very encouraging 8:1 contrast ratio and 45 ° viewing angle are reported for a 192 × 127 element display. The remaining two papers are relatively straightforward product descrip- tions of an EL terminal and an EL chip-set.

Ne//Ban/e~ Plessey Displays

Addlestone

VDU ergonomics and design

' D e s i g n i n g VDU work 'p laces : works t a t i on , e n v i r o n m e n t , o r g a n i s a t i o n a n d s y s t e m intro- duc t ion ' Benz, C., Grob, R., I-Iaubner, P. Verlag T0V Rheinland, 1983, pp 176, DM48

As the applications of visual display units increase, there is a need for guidance in the ergonomic aspects of their installation and use for those who have no specialist knowledge either of computers or of the human sciences. This compact text is

DISPLAYS, JULY 1985 159

directed at that need, and it makes a useful contribution. It is very well presented, with clearly organized text, properly annotated tables and diagrams, and many photographs of actual installations.

After a brief Introduction, Chapter 2, ~rhe VDU workplace as a work system' puts the emphasis on the complete system, involving equipment, workstation, environ- ment, work procedures, and the introduction of the system. It is especially important to consider the range of tasks to be performed, and the required flexibility in arranging the individual workstation com- ponents. Chapter 3, 'Basic ergonomic factors', sets out the basic principles, summarized in a sequence of 'rules', under the broad headings off physical activities (use- ful emphasis on posture, anthro- pometric ranges, thigh/elbow clearance); visual perception (rather extravagant detail on the psychophysics and physiology of vision); aspects of information pro- cessing (a somewhat surprising mixture of character design, contrast and anti-glare measures, symbol coding, screen formats and dialogue types); and psychological and sociological aspects (very brief comments on motivation, informa- tion for employees, training, and social organization). Thus, Chapter 3 provides a comprehensive, if somewhat uneven, coverage of

basic principles, while detailed recommendations are contained in the two following chapters. This separation of the basic discussion from the quantitative recommenda- tions may promote easy reference to Chapters 4 and 5, but it does lead to a certain amount of repetition in the respective chapters.

Chapter 4 presents data and advice on workstation design, with separate sections covering the desk (adjustable and non-adjustable), chair, footrest, VDU, keyboard, documents and document holder. Sufficient detailed measurements are recommended for all of these facets. As in Chapter 2, there is emphasis on the need for flexibility in arranging the main components of the work station (that is, screen, keyboard, document) and final sec- tion discusses the optimum layouts for different types of task. Chapter 5 gives data and suggestio~is on the design of the working environment, with considerable detail on illumi- nation requirements, and brief recommendations on the thermal and acoustic environments. A final section, replete with helpful photo- graphs of actual installations, sets out some useful guidelines on room arrangements for single and multi- ple VDUs. As would be expected, prime attention is given to the effects of natural and artificial light sources.

Chapter 6, 'Hints and examples

on job reorganization' makes some very general points about the need for care in re-organizing jobs and introducing the new requirements. Some before/after examples are given, showing changes made in workstation and ergonomics aspects, the latter usefully emphasizing enhancements and extensions to human skills.

Chapter 7, 'Hints and examples on preparing the user', discusses induction and training for new sys- terns, with one specific example. Chapter 8 contains ergonomic checklists for the design of VDU workplaces, essentially summariz- ing the detailed recommendations given in the preceding chapters. The reference list has 86 books and papers listed: only 13 are in English, but I doubt if the typical reader of this text will have need of further detailed information.

Altogether, this is a useful addi- tion to the literature on VDUs for non-technical readers. The princi- ples and specific recommendations are well organized and presented, and the emphasis on specifying tasks and allowing flexibility for different requirements is helpful. The text can be recommended as an introduction to the ergonomics of VDU work places.

David Wlu'tfield CEGB

G]oucester

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160 DISPLAYS, JULY 1985