Viewing The Display Screen
What about viewing the display screen itself? Certainly it is this modern device which must be used in various ways according to the job function that is causing much of the terminal operator discomfort.
It is our contention that, as they are in Europe, all terminals in North America will eventually be made with keyboards and screens separate. Therefore it is to this type of terminal we will address ourselves for ergonomic considerations.
As the units are separate, so should be the surfaces supporting them. And just as the keyboard surface requires height adjustability, the screen surface also must be, but to an even greater degree.
In many cases where discomfort problems have been recognized, such as eyestrain, the terminal is incorrectly blamed as the specific cause. In job functions such as data entry or word processing from source documents, the majority of eye contact is actually on that which is being processed, not the terminal. Though these individuals will look frequently at the screen, the total percentage of eye contact is quite limited. How can the terminal itself be the cause of discomfort?
Of course it all has to do with the incorrect positioning of the keyboard, screen and source data, individually and in relationship to each other. Yet the functional and physical requrements of each computer terminal operator can vary tremendously. Experienced terminal operators working from adjustable source document holders can be helped to work more comfortably at a table that allows the elevation of the VDT screen to a position where their eyes will read at an angle slightly down to the screen centre, at between 10 and 150 from the horizontal.
The copyholder should then be positioned as close beside-the screen face as possible to reduce the distance of eye movement between the source data and screen. In fact where possible and applicable, the copyholder should be positioned directly in front of the operator with the VDT screen immediately to its side. These adjustments will allow the operators to work in a fully upright and erect posture to minimize potential physical discomforts.
These specifications have been detailed in most of the data regarding the comfort of computer terminal operators that is available today.
Unfortunately, such specifications apply to only a minority of computer terminal operators, but this fact has largely been ignored by most of the end users, ergonomic "experts" and manufacturers of computer terminal support furniture.
Computer terminal operators who are unable to use copyholders, due either to the size of the source documents, the speed of their processing or just individual preference, will read from the desk surface. While most of these operators will have the majority of their eye contact on the source data, they do look at the terminal screen frequently.
When left in an elevated position it is then the angle and distance of head and eye movement between source data and screen that is actually causing most of the physical discomforts. Some companies have purchased lower tables to bring their terminal down to a more comfortable working height or that extend the keyboard towards the operator, only to cause eyestrain by increasing the reading distance to the source data on the work surface and postural problems as they lean forward in their chairs.
Efforts to read the data usually result in additional physical discomfort and postural problems.
Many others have not,yet recognized that a work surface angled from the terminal table at 45° - up to 60° will not only facilitate easy movement to the work surface, but also allow the.positioning of source documents at a closer reading distance to the individual.
The requirement for the positioning of the terminal screen for operators who read from the desk surface down as low as possible to a more even viewing plane with the source data, to reduce the distance of head and eye movement. This height should be even lower than the keyboard surface itself.
Reducing the distance between the keyboard and visual display screen becomes essential with inexperienced terminal operators, who have constant eye movement between keyboard and screen to confirm the choice of keys they will press.
Not reducing this distance can cause varying levels of eyestrain and fatigue for these individuals. This must not be ignored as the proliferation of terminals is ensuring that users without typing experience are quickly becoming the majority.
It is also essential that anyone who wears bifocals must have the visual display screen as low as possible. Such eyeglasses necessitate that the wearer read through the bottom part of the lens, a requirement that, if ignored, can cause headache, eyestrain or neck ache in a short period of time. Lowering the screen surface for these individuals has proven to be more acceptable than using prescription glasses made specifically for operating their terminal as such glasses inhibit the user from occasionally looking away from the terminal; something they often wish to do just to stretch or rest the eyes.
The rapidly growing introduction of video display terminals in office work has-given rise to a number of occupational hazards as stated earlier in this report.
Operator's visual fatigue and eye strain are some of the more comonly encountered symptoms. In the beginning of the sixties, when the first computers were introduced, there were bnly a few operators and they were highly motivated and willing to discover the "miracles" of computer technology.
The situation today is completely different since C.R.T.s are introduced in many job functions and the operators are very often more or less reluctant and passive witnesses to the computerization of their office tasks.
They do not necessarily consider such an evolution as progress if a large part of their job is changed into a more or less routine "Man-machine" relationship which, as well as being often monotonous, can be very trying for the eyes.
As stated. Setting up a C.R.T. display terminal implies that very close attention is paid to the workstation lay-out and taking account of the special requirements present.