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There are currently two important standards both derived from regulations originally laid down by Swedish authorities. MPR-II The standard originally proposed by the Swedish National Board of Measurement and Testing. It set maximum levels of electromagnetic radiation emitted by monitors, and has now been adopted as a world standard. MPR-II defines maximum permitted electrostatic, magnetic and electric field levels measured at a distance of 50 cm from the center of the monitor (see table). TCO In 1991, the Swedish Tjanstemannens Central Organization (TCO, Swedish confederation of Professional Employees ) set a standard even more severe than MPR-II, especially for alternating electric fields (AEF). The TCO standard is more severe since not only are the permitted field levels reduced compared with MPR-II, but the measuring distance is also reduced (see table). Electromagnetic radiation standards EMI (Electrical Magnetic Interference) The electrical and/or magnetic radiation coming from the working electrical or electronic equipment. EMS (Electrical Magnetic Sustainment) The ability of electrical or electronic equipment to function properly in the environment with electrical and/or magnetic interference. RETURN TO TOP OF THE PAGE F Flicker Very rapid variations in picture intensity caused by the finite time required for the electron beam to scan a picture onto the screen. Two kinds of flicker occur: line flicker caused by the electron beam scanning-in each line of the picture; and frame flicker (or field flicker if the picture is interlaced) caused by the frame repetition rate of 50 frames/second. Frame flicker is noticeable with GUI and DTP software (which have a light background), and can be very disturbing, especially for those who work regularly with displays - contributing to eye strain, headaches, visual blurring, stress, etc. The problem can, however, be eliminated by increasing the refresh rate (number of frames/second) of the monitor to a value above around 70 Hz. Sensitivity to flicker appears to diminish with increasing age. RETURN TO TOP OF THE PAGE H Hertz The unit of frequency named after the physicist Heinrich Hertz (1857-1894). 1 hertz (Hz) is equal to 1 cycle/second. Horizontal dot pitch See Dot pitch. Horizontal scanning frequency Also called line frequency and expressed in kHz, it is the number of video lines written on the screen every second (from left to right). The higher the horizontal scanning frequency, the better the resolution (i.e., the higher the resolution and/or the higher the refresh rate). RETURN TO TOP OF THE PAGE I INF File INF file (Information File) Information (INF) files store information in a specific format. The set-up functions retrieve information from the INF file to use when performing installation operations. Examples of the type of information stored in an INF file include INI and registry changes, file names, and locations of the source files on source media. Interlaced/non-interlaced Interlaced. The method of writing a picture on the screen by initially writing all even lines and subsequently writing all odd lines of the picture. Result: The complete picture is composed of two interlaced half pictures (or fields). With interlacing, a vertical (or field) frequency of 50 Hz means a picture (or frame) frequency of 25 Hz. Non-interlaced. The method of writing a picture on the screen by successive video lines of the picture so that a full frame is written onto the screen in one vertical sweep of the beams. With a non-interlaced display, a vertical frequency of 50 Hz means a picture (or frame) frequency of 50 Hz. At any given resolution, non-interlaced modes are preferable to interlaced modes; however, generation of non-interlaced modes is more expensive. RETURN TO TOP OF THE PAGE L Linearity The degree to measure the actual location of a pixel on the screen corresponds with its intended location. ( see figure ) Line frequency See Horizontal scanning frequency. Low-emission monitor A monitor that complies with international standards on radiation. See Electromagnetic radiation standards. Low-frequency electric and magnetic fields Alternating fields generated by the deflection yoke. These are subject to increasing attention, notably by governing authorities, the trade and the press. Although there is no scientific evidence that monitor emissions are harmful, much effort has gone into reducing emissions on the principle of better safe than sorry. Currently, there are two areas of interest: very-low frequency (VLF) electric and magnetic fields extending from 2 kHz to 400 kHz, and extreme low frequency (ELF) fields extending from 5 Hz to 2 kHz. See also Electromagnetic radiation standards. RETURN TO TOP OF THE PAGE M Moire effect A fringe pattern arising from the interference between two superimposed line patterns. In a monitor it comes from the interference between the shadow mask pattern and the video information (video moire), and between the shadow mask pattern and th...
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