(1)
(2)
(3)
Fault class Type 1** Type 2*** Type 3****
I 0* 0* 0*
II 2* 2* 5*
III 5* 15* 50*
IV 50* 150* 500*
Fault class Resolution Number of pixels Type 1** Type 2*** Type 3****
II
1,024 x 768 786,432 2 (1,579)
TCO 06: Sets particularly high standards of colour fidelity, brightness levels and uniform
illumination. These factors are very important for image quality for applications with
fast-moving animation.
TCO 03: Quality seal from Sweden, defining strict ergonomic and environmental com-
patibility standards (TCO 03, as of 2003).
ISO 13406-2: Ergonomic requirements laid down by the International Standards Organ-
ization (ISO) relating to image quality for flat screen displays.
TÜV
1)
Ergonomics: Defines high ergonomic requirements, including safety standards
and low radiation.
TÜV GS: Safety tested in accordance with work and operating safety guidelines and ergo-
nomic requirements for visual display terminals under ISO 9241-3.
CE mark: Manufacturer’s declaration in accordance with EU guidelines relating to prod-
uct safety and electromagnetic compatibility.
Energy Star®: An energy-saving seal of approval established by the EU and the USA for
office appliances which operate with high energy efficiency.
ISO 13406-2
Important quality criteria
ISO 13406-2 is the testing standard used for the TÜV Ergonomics inspection and involves
controlling the ergonomic properties of display screens. ISO 13406-2 has been specially
developed for the assessment of liquid crystal displays, whilst ISO 9241-3-7-8 relates to
CRT displays.
TCO seal
The TCO seal is awarded by the Swedish employees’ trade union, ‘Tjänstemännes Central
Organisation’ and has become a general standard for display screens. TCO 99 and TCO
03 are currently established. The numbers indicate the year the standard first appeared.
TCO 99 regulates particular quality standards such as viewing angle and contrast. TCO
03, a stricter standard dating from 2003, also lays down particular environmental and
radiation standards. Harmful substances such as cadmium and lead were banned from
monitors. The Swedish trade union guarantees that quality standards are maintained by
employing random testing.
1)
TÜV = Technical Control Board
Important criteria for evaluating LC displays:
• Displayluminance
• Contrast
• Reflection
• Uniformityofluminanceandcolours
• Fontanalysis
• Pixelfaultclass
• Screenflicker
Viewing direction classification
ISO 13406-2 includes a definition of viewing direction classes. These classes relate to
whether an individual user is viewing the screen from the front (class IV), for example,
or whether several people can see the display from different angles (class I).
Reflection classification
ISO 13406-2 also takes into account the reflection properties of flat screen displays. This
is particularly important in very bright and well-lit environments, as acceptable image
quality should still be able to be achieved in such surroundings. The standard thus
defines three quality classes. The wording of the standard is, however, not very precise:
‘Generally suitable for office environments’ – indicates that the monitor can also be
used in difficult circumstances, such as at workstations very close to windows.
‘Mostly suitable for office environments’ – suitable for most office environments, if
workplace ergonomics are taken into account when the monitor is set up.
‘Suitable for office environments with controlled luminance’ – suitable for rooms
without windows or with indirect daylight, for example.
Pixel fault classification
With respect to pixel defects, a new standard ensures transparency by establishing pixel
fault classes. These must be indicated in the technical specifications provided with the
appliance. In adhering to this standard, the manufacturers are obliged not to exceed
established pixel fault quotas in series production.
* Per million pixels.
** Illuminated pixels (white).
*** Dark pixels (black).
**** E.g. defect red, green or blue sub-pixel (always lit or unlit).
One LCD pixel consists of three red, green and blue sub-pixels.
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