Analytical note to the issue on the use by JSC “Tekhnopribor” of light-emitting diodes in working out of energy- saving fixtures, for housing and communal services and street illumination.

 According to the statistics, nowadays up to 20 % of all electric power in the modern world is spent on illumination. Semi-conductor electronics and optoelectronics are the most dynamically developing branches of technics. What is to expect from semi-conductor technologies in the field of energy-saving? The most obvious (but not unique) prospect is an alternative kind of illumination which should take a place of traditional to us bulbs. Let's consider the efficiency of energy transformation of various lighting devices. The usual bulb radiates only 10 % of received energy in the form of useful not even white, but yellow light. The rest 90 % is spent for air heating because the incandescent bulb filament  is shone in an infra-red range and only the small share of light radiated by a bulb is necessary on a visible part of a spectrum. The average duration of bulbs’ burning is 1000 hours. The index of thermal light sources colour rendering “Ra” corresponds to an estimation "perfect" and is close to 100. The average price is 1000 roubles.

 The unique way of increase in efficiency is rise in temperature of an incandescent filament. For this purpose a bulb flask is filled with gas with addition of halogen elements (iodine or bromine steams) under high pressure to provide that the filament did not evaporate at more heat, — the bulb turns into halogen. The flask of halogen bulbs is made from the quartz glass steadier which is more heat and chemical influence resistant, thanks to it the size of halogen bulbs is several times less in comparison to the usual bulbs of the same capacity. The halogen bulb radiates in a visible range up to 15 % of the spent capacity. Such efficiency does not also suit us. The average operation time of halogen bulbs is 2 500 hours. The index of colour rendering “Ra” is close to 100. The average price is 4 000 roubles. Two essentially different sources of light are: luminescent lamps and light-emitting diodes. Luminescent tubes shine, when there is an electric category that lights up in them. In inert gas filling a tube (the neon, argon, helium) dissolve mercury steams. Atoms of mercury under the influence of the electric category come off electrons and, accelerated by electric field face other atoms of mercury, giving energy in the form of ultra-violet radiation. The tube inside is covered with a luminescent material which absorbs ultraviolet and radiates it already as visible light. The average operation time of modern luminescent lamps is 8 000 hours. The average price is 9 000 roubles. The index of colour rendering “Ra” of luminescent lamps of various types is within the limit from 60-80.

 But the most perspective variant is light-emitting diodes. The light-emitting diode as a matter of fact is nearly the same semi-conductor diode which is applied in electric schemes as the rectifier, it is not made only of silicon, but of special, so-called «open zone» semiconductors. It radiates directly visible light. Colour of a light-emitting diode luminescence can also be selected, choosing as a basis a semi-conductor material with the necessary width of the forbidden zone. The operation time is up to 80 000 hours. The price is comparable and constantly falls.

 Intrusion of semiconductors into illumination has begun just there where colour light was necessary. First of all, these are traffic lights. Low-powered light-emitting diodes are applied there and their advantages are obvious. Still it is necessary to notice that light-emitting diodes begIn to be widely applied for architectural constructions’ illumination and as light sources in fixtures for alarm protecting fires and creation of light compositions.

 But most of all we are interested in white light. The most direct way of this white light reception is a mixture of red, green and dark blue, as on the TV screen. But it is easier and more effectively to take a dark blue light-emitting diode, put on it a luminescent material which will transform part of the dark blue light into yellow — as a result of their mixture we get white light. The basic making part of powerful (from 1 to 10 W) white light-emitting diode of high brightness (HB LED - a light-emitting diode) is the complex semi-conductor connection consisting of nitrides of gallium and indium (InGaN), created by escalating on a substrate from silicon carbide (SiC). This technology provides the highest indicators of cost-efficiency parity for light-emitting diode light sources. The average price of such light-emitting diode is about 30 000 roubles. But their cost gradually falls. 

 When technologies of extra-bright light-emitting diodes provide their price competitiveness in comparison with all other kinds of lamps, it will be necessary to turn off lamp manufacturing. Manufacturers of light engineering themselves destroy the business but if today they do not make it,tomorrow there will be others doing the same thing. To make high-quality light-emitting diodes in the necessary quantity, merge of several branches — electronic, electrotechnical and light industries is required.

 Nowadays in Belarus crystals, on the base of which light-emitting diodes are assembled, are not made serially. JSC "Tekhnopribor", Mogilev as the enterprise familiar with light-emitting diode technics could take up elaboration and development of release of the wide range of light-emitting diode energy saving fixtures of different function. Nowadays in the quality of white light sources there applied highly efficient extra bright light-emitting diodes with light return up to 90 lm/W and service life till 100 000 hours. The basic manufacturers of such light-emitting diodes: Seoul Semiconductor (South Korea), Nichia Chemical Corp (Japan), Cree Inc (USA), Vishay Electronics (Germany), A-BRIGHT (Taiwan, China) and  "Cover-light" (Russia).

 It allows to create energy -saving fixtures for functional illumination of open spaces, parks and foot zones, railways and highways, tunnels, industrial and office premises, warehouses, shopping centres, shops, shop-windows, entrances and ladder platforms. Let's list advantages of light-emitting diodes and, accordingly, light-emitting diode fixtures produced on their basis:

— Service life up to 100 000 hours that is equivalent to 10 years of continuous work or 20 years of work in a mode of real city illumination. It is caused by absence of an incandescent filament, thanks to not thermal nature of light radiation. It  will  be necessary to replace a halogen lamp about 80 times, metalhalogen — 20 times, luminescent — 10 times.

— High profitability of energy consumption. Energy consumption decreases 4-5 times in comparison with fixtures on the basis of traditional lamps and in 2 times in comparison with the compact energy- saving luminescent lamps.

—      Ecological safety and absence of necessity of special recycling: fixtures on diodes do not contain any mercury, its derivative and other poisonous or harmful components that are apparent defects of all luminescent lamps.

 — High mechanical durability and reliability, owing to absence of a glass flask and an incandescent filament.

— Contrast of LED light considerably exceeds the contrast of gas-discharge lamps, thereby provides considerably the best clearness of enlighted objects.

Index of colour rendering “Ra” is 80 and more. It is less than thermal light sources, but all the same corresponds to estimation "perfect":

— The indicator of light stream use is close to 100 %, whereas at standard street fixtures — 60-75 %. Powerful light-emitting diodes represent ideal light sources with the built- in correcting optics that provides ideal formation of the set diagrammes of light stream direction.

—Absence of harmful effect of low-frequency pulsations peculiar to gas-discharge light sources. The light stream of light-emitting diodes is constant, as well as natural light of the sun that provides psychological and visual comfort.

—total absence of danger of an overload of electric system at the moment of turn on. The consumed and starting current of the light-emitting diode fixture is equal to 0,7–1,1Am and at the fixture with a gas-discharge lamp consumed current is 2,1 Am, but starting 4,5 Am. To have the optimum of technical performance data of gas-discharge lamps there required additional systems and devices.

—      Instant ignition at giving the consuming pressure and independence of working capacity from low temperatures, unlike in widely used for street illumination mercury (luminescent) and sodium (metal halogen) lamps.

—      At installation of light-emitting diode fixtures the cable of smaller section (that is essential item of economy) is required.

—      Economy of labour as the fixture on light-emitting diodes does not require maintenance service throughout the entire service life.

—       However, light-emitting diode light sources for the present remain to be expensive. But it is possible to ascertain with confidence that we are on the threshold of the beginning of mass penetration of light-emitting diodes into the sphere of general illumination. It occurs at the moment of time when the prices for energy have considerably increased, and the society, in its turn, gets worried about the environment. All it considerably increases interest in application of energy- saving technologies and systems, and advantages of light-emitting diode technics here are conclusive.