If you already have poor sharpness of vision, low-quality screens can make things even worse. Apart from eye problems, tenseness, fatigue, and many other disorders can be caused.
The latest technological developments are triniton, or black-matrix, screens and TFT flat screens. Unfortunately, flat screens are still relatively expensive. There are extensive standards that regulate the readability of the depicted information. When buying a screen, it is recommended to study the extensive standards to avoid a wrong purchase. One thing is certain: a good screen is usually expensive. The normal tube screens do not last forever. They only retain their focus and contrast for a few years.
All depicted characters should be sharply defined and clearly legible up to the edges of the screen. A positive representation (dark characters on a light background, such as in a book) is recommended.
As the depicted characters must be large enough, a 17-inch monitor is recommended, at least for graphical user interfaces (like KDE). For the processing of CAD, layout, and graphics, it should be 21 inches.
It is especially important that the screen does not flicker. In concrete terms, the minimum sync frequency with 15-inch monitors should be at least 73 Hz. However, 85 Hz is recommended. For larger screens, such as 21-inch, 100 Hz is a good value.
Luminosity and contrast should be variable. The focus of the characters should not differ with adjustments of brightness or contrast.
The image should be free from distortion and show no color errors.
To avoid reflex glare, a good antireflective coating of the screen surface is recommended.
The screen should be rotatable and inclinable. A vertical adjustment is recommended.
Colors make the displayed information easier to comprehend. However, the display of colors can also be straining for the eyes because different colors are refracted differently by the lenses. For red colors, people are farsighted, but for blue colors people are nearsighted. Older screens often have convergence errors — the three beams of the screen tube are no longer aligned precisely, so colored borders appear around letters, for example.
Electromagnetic radiation emitting from the screen should be kept to a minimum.
A screen put in the wrong place leads to a cramped posture at work, which can cause illnesses. A work table that has insufficient depth often prevents the screen from being placed reasonably. The natural position of the head and arms is designed for work that lies in front of the body.
Ergonomics specialists have developed their own guidelines for the “vision and gripping area.” These reject placing the screen to the side. An exception is only when the screen is rarely used. A reason for this placement is the fact that even the required minimum 80 cm worktable depth is insufficient with a large screen and the use of working documents. Often the screen is placed — as shown in many PC manual pictures — on top of the computer case. This also leads to an unnatural posture. Observe yourself while you are reading. Are you looking straight ahead or slightly down?
Shoulder, keyboard, and screen should be in one line so you always look directly at the screen. This rule does not necessarily need to be observed all the time.
Ultimately, the workstation should be individually adapted to the person and the working task. Flexibility is the key. Easily movable, rotatable, and, ideally, screens that retract into the table are encouraged.
A comfortable visual distance varies individually. At least 50 cm is required. Some people need considerably more.
It is a good idea for users to look away from the screen from time to time. In this way, their eyes can adapt to a different distance.
If a document is being copied, it should be at the same distance as the screen to avoid frequent changes of focus.
The difference in luminance between the direct working area, the screen, and the immediately surrounding areas, such as the screen case, should not be more than three to one. For this reason, computer cases in offices are not black. The difference between the working area and the surroundings should not be more than ten to one.
Shiny areas create large differences of luminance. This is why office furniture is not available in bright colors and has a matt surface.
To minimize the reflex glare on the screen, the screen and the keyboard should be arranged so the line of vision is parallel to window panes. The further the screen is away from the window, the better.
The screen should not be directly under a lighting strip, but to the side of it. The line of vision should be parallel to the lighting strip.
It is well-known that the keyboard arrangement derived from the typewriter is not necessarily ergonomic. During typing, the fingers, hands, arms, and shoulders are strained. This leads to tense muscles. The strain caused by a keyboard of inferior quality adds up over time. Unfortunately, the tiny movements produced while typing are very difficult to measure. Risk factors include the RSI syndrome.
The keyboard is, without doubt, the most frequently-used input computer input device. Therefore, it must be especially well-designed. Ergonomic specialists often criticize the fact that the Shift and Enter keys are too small. Another basic problem is the cable, which is often too short, preventing a comfortable individual placement. Consider buying a wireless keyboard or an extension for the cable.
The keyboard should be separate from the screen. It should also be inclinable, but set in a stable position (sufficiently large, rubber-coated feet).
The middle key row should not be more than 30 mm above the surface of the table.
There should be room to rest your hands in front of the keyboard. If there is no built-in wrist pad, get one.
The marking must contrast with the color of the plastic and be easy to read. The keyboard should have no intense color and a satin-matt finish.
For the keyboard legend, a dark script on a light background is recommended. Black keys are not ergonomic.
The form of the keys should enable light and accurate typing. The lift of key should be 2–4 mm and the working point should be distinctly felt. Here 50–80 g is recommended as the force of the key depression stroke.
Those who type a lot should take regular breaks.
Learning the touch system helps because the workload is distributed across all fingers.
Split or individually separable keyboards are something to which you have to get accustomed, but nevertheless are an alternative worth considering. They have been constructed according to the latest ergonomic findings and are already recommended in some standards. They prevent wrist strain to the side.
The keyboard of a notebook or laptop cannot correspond to the standards because of the crowded keys. A notebook should therefore not be used as workstation equipment unless it is linked to an external keyboard and mouse.
Due to the advance of graphical user interfaces, users are practically forced to use a mouse. The intensive use of the mouse can cause not only fatigue, but also disorders in the hands, arms, and shoulders. An example of this is RSI. The danger increases when a “bad” mouse is used. So far, there are no commonly accepted standards for an ergonomic mouse. Often a PC is sold with the standard mouse. This mouse should certainly be examined closely. Is the mouse really suitable or should it be replaced by a better one? Have the dealer unpack several mice for you to try. The cable is probably too short. Ask the dealer to give you an extension. Evaluate your own mouse use. Can you reduce the use of the mouse? Many professional programs with a lot of interaction do without any mouse clicks. Learn how to use shortcuts to operate programs. It takes time to learn, but you can work up to four times as fast. Often a combination of mouse and keyboard operation is recommended.
The ergonomic mouse feels good in your hand. The keys should not be too close or too small. There are even mice for children's hands.
Your fingers should be able to rest on the keys in a relaxed position.
The mouse should be next to the keyboard. Left-handed users have an advantage because the keyboard has several function keys and the numerical key block between letter keys and a mouse on the right side. These extend the gripping distance. If you are left-handed, get a mouse for left-handers. Learning keyboard codes reduces the workload on the complete arm. An arm-shoulder area strengthened by the appropriate physical training can deal better with overstrain for a short time.
The cable should be long enough. If necessary, purchase an extension. A wireless mouse is a luxury.
The mouse needs a proper base to function well. Get a good mouse pad.
Pay attention to the mouse driver. Good mice have mouse drivers with a multitude of functions. You can, for example, adjust the cursor movement exactly according to your requirements or assign special instructions to the different mouse buttons. The double-click might be placed on the middle button with the mouse driver.
Make sure you adjust the acceleration and double-click adjustment of the mouse to your own preferences. Some people work with the mouse from the hand joint. Others prefer moving their complete forearm.
An alternative to the mouse is a trackball. Here, you move a ball inside a stationary casing to control the mouse pointer. In contrast to the mouse, the trackball reduces the movements in the hand and arm area.