TCO Monitor Standards

In 1995, TCO modified the requirements for visual ergonomics and added a range of conditions to cover environmental issues, including the use of certain chemicals in manufacturing and the recycling of components. The most stringent standard so far, and the result of collaboration between the TCO (The Swedish Confederation of Professional Employees), Naturskyddsforeningen (The Swedish Society for Nature Conservation) and NUTEK (The National Board for Industry and Technical Development in Sweden), TCO95 became the first global environmental labelling scheme. It was more comprehensive than the German Blue Angel label and more exacting than the ISO international standards. The display, system unit and keyboard can be certified separately and the manufacturer’s environmental policy is addressed at every stage from production to disposal. Over and above TCO92, the product may not contain cadmium or lead, the plastic housing must be of biodegradable material and free of brominated flame retardants and the production process must avoid use of CFCs (freons) and chlorinated solvents. The emission and power saving requirements remain unaltered although picture performance and luminance uniformity have been addressed.

TCO standards also require that screens be treated with conductive coatings to reduce the static charge on the monitor. Although static electricity generated on the front surface of a CRT has been alleged to be a factor in a number of health risks, it has not yet been confirmed.

TCP99 is the latest iteration of the standard. TCO99 doesn’t change the emission levels from those in the previous versions, but it does alter the testing procedures to deal with certain loopholes. The new approval mainly concentrates on improving the visual ergonomics requirements. Improvements in visual ergonomics include better luminance uniformity and contrast. There is also a new requirement that screen colour temperature adjustment, when present, should be accurate.

To reduce eye fatigue caused by image flicker, the minimum required refresh rate is increased to 85Hz for displays of less than 20in, with 100MHz recommended, and to a minimum of 75Hz for 20in or greater. Although harder to control, there are measures to address the problem of screen contrast in the office environment. To help manufacturers achieve the right balance between anti-reflection treatment and the minimum amount of light reaching the user, a minimum diffuse reflectance level of 20% is specified.

More exacting attention is paid to power saving and environmental impact, with TCO99-certified monitors saving up to 50% more energy than TCO95 displays. There’s a different requirement for monitors with USB hubs, which can suspend at 15W and restart in three seconds; non-USB monitors must suspend at 5W. Manufacturing requirements are more stringent too. No chlorinated solvents may be used and product vendors must provide corporate and domestic customers with a recycling path using a competent recycling body.

The following table shows the key improvements in TCO99 compared with its TCO95 predecessor:

Luminance uniformity >1.7:1 >1.5:1
Luminance contrast Measured at 10% of the diagonal to the edge Measured at 5% of the diagonal to the edge
Magnetic field requirements
Front frame reflectance No standard At least 20%
Measured 30cm in front of and 50cm around the screen 5Hz to 2kHz at <200nT Same standard measured at maximum brightness/contrast
Measured 50cm around the screen 2kHz to 400kHz at <25nT Same standard measured at maximum brightness/contrast
Alternating electric field requirements
Measured 30cm and 50cm in front of screen 5Hz to 2kHz at <10V/m (Volts per metre) Same standard measured at maximum brightness/contrast
Measured 30cm in front of and 50cm around the screen 2kHZ to 400kHz at <1.0V/m Same standard measured at maximum brightness/contrast
Power saving Suspend mode at < or = 30W Suspend at < or = 15W (for USB hub monitors), < or = 5W (for non-USB monitors)
Environmental controls No standard No chlorinated solvents; compulsory list of potentially hazardous plastics used

Monitor manufacturers Acer and Taxan spearheaded the drive to certification, hitting TCO99’s launch date of 29 October 1998.