Displays, Health and the Environment
The Swedish TCO95 approval of personal computers is the labelling scheme with the broadest scope. TCO95 covers the complete PC, including the display. TCO95 differs from many other labelling schemes in that it encompasses ergonomic qualities, emissions, energy efficiency, and the environmental impact of both the product and its production.
Created and operated by an organisation (The Swedish Confederation of Professional Employees) representing over a million professional employees, TCO95 is expressly aimed at improving the working conditions of people for whom the computer is the most important tool.
TCO95 is expressly designed to improve the working conditions of a large majority of professional employees who depend on efficient IT support in their work. These people want to work with PCs that are user-friendly and do not pose a health risk to the user. Based on the needs of TCO members, TCO95 approval is aimed at promoting technical development which allows professional employees continuously to improve their professional skills, says Dr Kjell Fransson of TCO Development Unit.
He stresses the global nature of TCO95, requiring that the approved product and its production process meet the same standards regardless of where the product is manufactured or sold.
The specific criteria that PC equipment must satisfy to qualify for TCO95 approval are based on TCO members accumulated knowledge and working life experience. To meet the wishes of our members, we work together with experts and scientists to formulate quantitative criteria and methods of measuring the defined parameters," Dr Fransson explains.
As far as the display is concerned, the demands and expectations of the professional PC user centre on the quality and adjustability of the picture. The picture must be sharp and undistorted across the screen. Defects make themselves felt as undue strain on the eyes.
TCO95 standards for the quality of the display image are mainly based on the ISO 9241 international standard. Some of the requirements are tighter than the corresponding ISO requirements. All the Nokia displays of the new family to which the Nokia 447Za belongs have both ISO 9241 and TCO'95 approval.
The standards define a testable minimum level for the ergonomic visual qualities of the display image. The image must be of sufficient brightness (luminance). It must be free of flicker and distortions (variation in symbol size and linearity across the screen). The image is free of flicker if the displays refresh rate is sufficiently high. The value recommended by TCO95 is 80 Hz. All the new Nokia displays are free of flicker by this standard.
Low Electromagnetic Emissions
Some display screen users are concerned about the possible danger to health of alternating electric and magnetic fields generated by the display. TCO95 defines upper limits for these low frequency fields. Compliance with the limits is measured at the highest image resolution.
The fields are measured both in front of the display and around it over two frequency bands. In front of the display the fields are measured at 30 cm away in the band of 5 Hz to 2 kHz and in the band of 2 kHz to 400 kHz. The fields are measured at 50 cm around the display in the 2 kHz to 400 kHz band.
The compulsory emissions values of TCO95 are based on the ambition of reducing the alternating electrical fields to as low a level as it is technically possible to achieve, so as not to burden the working environment with unnecessary factors, says Kjell Fransson.
The actual values are as follows. The alternating electric field measured in front of the display must be less than 10 V/m for the low frequency band. The fields around the display and in front of the display must be less than 1 V/m for the higher frequency field. The compulsory values for the magnetic fields are 200 and 25 nanotesla, respectively.
The 17-inch Nokia 447Za consumes less electricity than a 100-watt light bulb, as against 120-150 W for ordinary 17-inch displays. The potential monetary savings can be readily quantified. TCO95 sets no limit on the displays power consumption in the working mode, but it does define upper limits on power consumption in the energy saving and off mode. The limit on the energy saving mode is 30 W, and that on the off mode 8 W.
Power must not be saved at the cost of user ergonomics, however. TCO95 requires that the user resuming work after a break have the display, which has switched itself into the energy saving mode, back in service within three seconds. Having to wait longer for the display to be activated is a possible cause of stress, Dr Fransson states.
Energy efficiency benefits the environment through a lower consumption of electricity. The environmental protection requirements proper of TCO95 cover the product, the production processes at the manufacturing plant, and packaging.
Manufacturing and packaging must not utilise or generate harmful substances such as CFC, HCFC or heavy metals. The product must not contain hazardous waste, such as cadmium or mercury.
The environmental focus is increasingly shifting on recovery or recycling of materials. Unlike the German Blue Angel environmental label, TCO95 does not require the manufacturer to accept back the product, but it provides for growing recycling of materials. In requiring that all plastic components weighing more than 25 grams must be labelled and that the variety of plastics used should be kept to a minimum, TCO95 prepares the ground for the recovery and recycling of plastics, an arrangement waiting to become financially feasible.
Ecological demands on the displays are a new area. At the moment, they are perhaps the most difficult demands to meet. However, for TCO members, ergonomics is the most important area. What the professionals require of the display today and will continue to require in the future is high usability. A display that is easy and safe to use supports the professionals in their work, Kjell Fransson states.