Monitor Ergonomics - Choosing the right monitor for you

By Hugo Bos – Ergonomics Manager at BakkerElkhuizen

Choosing the right monitor is very important to ensure easy reading of data on the screen, and also
to provide comfort and avoid eye strain.

In recent years, two conflicting trends have been evident. On the one hand, monitors are getting bigger: 17” flatscreens are already difficult to find and 22” to 24” screens are no exception any more. On the other hand, the monitors are also getting smaller, as an increasing number of people read email and use other applications on a 12’’ or 13’’ laptop, their telephone, Blackberry or iPhone. The small displays are, of course,
ideal for mobile use, but they are too small for lengthy and intensive monitor use. Another trend is the use of dual screens or widescreen monitors whose display can be split into two.

First check which applications are used the most within the organisation.

Organise a user test with various different monitors.

Ensure that you involve users from each organisational component.

Image quality
In recent years, monitor specifications have been greatly improved and differences in quality have become less significant. In other words, the image quality of most monitors may be considered good.

The distinguishing characteristics are as follows:

• Contrast (a standard contrast 450:1 (number of gray tones) is adequate for normal use, a higher value is recommended for a sharper display of colour);
• Resolution (measured in pixel density; the higher the resolution, the more information can be displayed);
• Brightness (under normal light conditions, 250 cd/m2 is enough; when extra brightness is needed, for example when working outside or in a brightly lit environment, 350 cd/m2 or more is recommended);
• Energy consumption (20-35 W is relatively low, also look for the energy star label).

Screens with a glossy surface are increasingly used for laptops. The advantage of such a screen is that the contrast and colour intensity are better. This is important when viewing films (at home), but is not ergonomically recommended because this creates reflections on the screen.

Choose a high-quality screen with contrast of min. 450:1, brightness of at least 250 cd/m2 and a low energy consumption of 20-35 W. Preferably not a ‘glossy’, but a mat surface.

Font size
The greater the resolution of the screen, the more information can be displayed and the sharper the image. A high resolution is in principle favourable, as the image is sharper. However, a relatively small screen (15” or less) together with a high resolution is sometimes chosen. In these cases, it can occur that fonts and icons are displayed too small.

A good ratio between font size and viewing distance is between 1:150 and 1:250 (depending, of course, on one’s eyes and any eye disorders, light conditions, etc.1). For a font size of 3.5 mm high, the optimum viewing distance is 3.5 x 200 = 700 mm. This lies well inside the range of the ideal viewing distance (between 60 and 80 cm).

Provide for a viewing distance of 60-80 cm, where the font size is between 3 and 5 mm.

For small fonts, increasing their size is recommended. This can be done in three ways:

Dual or Multi-screen use
An increasing number of computer users nowadays works with two or more applications at the same time, where information from one application must be compared with that of another, or where information must be copied from one to the other. In these cases, displaying both applications next to each other is easiest and works much more efficiently. This can be achieved by using two monitors adjacent to each other,
or a widescreen flatscreen that is split in two. Scientific research shows that by doing so, 33% fewer errors are made with certain tasks, and productivity increases by more than 11% (J. Colvin, 2004).

Whether you choose a widescreen monitor on which dual screen display can be facilitated or two separate monitors next to each other depends on the type of task that has to be performed. In principle, more can be displayed on two separate monitors than a widescreen monitor. The following table indicates how much information (number of characters) fits on a screen:

Dual screen 17": 2,621,440

Dual screen 19": 2,621,440

Dual screen 21": 3,840,000

22" widescreen: 1,764,000

24" widescreen: 2,304,000

Clearly, more information can be displayed on the 17” and 19” dual screen than the 24” widescreen.

Laptop or flatscreen
Screen problems involving too small characters and incomplete information are mainly a problem with laptops with a screen smaller than 14” or 15” and a very high resolution. Connecting an external monitor is prudent when one must work with a computer for lengthy periods (i.e. longer than 2 hours). This monitor can be connected to a laptop directly or via a docking station. The laptop screen can then be used as a second screen, thereby creating a dual screen. See photo below.

When using a number of applications at the same time, choose a dual screen solution.

To display a lot of information, two separate monitors next to each other (e.g. 2 x 19”) are recommended above a 22” or 24” widescreen monitor.

Ensure that the screen is big enough. 12” or 13” screens are usually too small for lengthy use. Many organisations choose a 15.4’’ laptop with a resolution of 1280x800 or 1024x768 as standard.

If using a number of applications at the same time, an extra separate monitor is recommended.

 

1. Source: Handboek Ergonomie 2009, P. Voskamp, PAM van Scheijndel, KJ Peereboom.