- History of LED lamps
- How the LED lamp works and works
- Pros and cons of energy saving LED bulbs
- How to choose an LED lamp for your home
In this Article: History of LEDs LED lamp – device; characteristics of the LED lamp; manufacturers and prices; choosing an energy-saving lamp for home.
What kind of lighting should we have in our homes? On this score, there are two opinions: households – the light should be pleasant and not harsh; leaders of the country – the lighting of houses should consume as little electricity as possible. The inexorable rise in prices for energy carriers is little understood by the average man in the street, he is more interested in the question “why these same energy-saving lamps are so expensive.” This article will consider in detail energy-saving LED lamps, which in the very near future, regardless of the desire or unwillingness of the average consumer, will illuminate our homes. Let’s figure out if they are as good as they are described.?
History of LED lamps
It all started back in 1907, when the English engineer Henry Round, turning off the lighting in the laboratory, accidentally noticed a glow around a diode contact under voltage. He decided that the glow was caused by some mistake in the calculations and did not pay special attention to this, although he noted this fact in the report..
Oleg Vladimirovich Losev
16 years after this event, the Soviet physicist Oleg Vladimirovich Losev began to study the strange glow that occurs at the soldering point of the contacts of a silicon carbide (carborundum) diode. Losev never found out the nature of the glow, noting that there was no heating to high temperatures – the reason for the glow was hidden in some kind of electronic process, unknown to science in those years. The results of Losev’s research on the glow of diodes were translated into several languages and published in a number of scientific journals, but did not arouse much interest. At the beginning of the 20th century, familiar lamps with incandescent filament were considered quite sufficient and indispensable – there was no need to invent something new.
Sustained interest in the glow of diodes arose in the second half of the last century, when the American engineer Rubin Brownstein announced his discovery – diodes made of gallium arsenide (GaAs) emit infrared rays when powered. According to the engineer, exactly the same radiation was observed by him in diodes made of indium phosphide (InP), gallium antimonide (GaSb) and consisting of a silicon-germanium alloy..
The first infrared diode was patented in 1961 by American researchers Gary Pitman and Robert Byard. But it was impossible to use such diodes to illuminate premises, because infrared rays are outside the spectrum visible to the human eye.
American scientist and inventor Nick Holonyak
The creator of the full-fledged LED was Nick Holonyak, Jr., who in 1962 created a full-fledged LED-light emitting visible red light. It is Holonyak who is considered the “father” of LED lamps. 10 years later, his student George Craford created the first LED to emit yellow light, and also tenfold the brightness of red and orange-red LEDs..
However, the new light sources were not in particular commercial demand – of course, because the cost of one LED was at that time $ 200. The first commercially successful production of LEDs in 1968 was established by the American company “Monsanto”, specializing in chemical products, these were LEDs from alloys of gallium arsenide and indium phosphide. It was Monsanto that made LEDs popular and widespread in electronic calculators and digital watches — from 1968 to 1970, the LED monopoly sold twice as many products as in every previous month. The introduction of LEDs into electronics is due to Hewlett-Packard, which was the first to appreciate the value of LEDs for electrical appliances and actively purchased them from Monsanto..
In 1970, Monsanto’s monopoly in the LED market was ended – using semiconductor chips from Dr. Jean Ernie, the American company Fairchild Semiconductor launched the production of cheap LEDs worth five cents each.
For decades, LEDs have been actively used in consumer and industrial electronics, but not for indoor lighting. The idea of creating full-fledged LED lamps that can illuminate our homes better than any “Ilyich lamps” came from Shuji Nakamura, who worked for the Japanese company “Nichia Corporation” – it was under his leadership that the company’s engineers created the first high-brightness blue LED in 1993.
The first LED emitting bright white light was created not so long ago – in 1997, the American engineer Fred Schubert became its creator..
Today, energy-saving LED lamps already exist, but they are still being improved, because the first LEDs, the light intensity of which became equal and, subsequently, exceeded the brightness of incandescent lamps, appeared only at the beginning of the 21st century..
How the LED lamp works and works
The device of any modern LED lamp is as follows:
- base. A standard element of any lamp, designed to be screwed into the lamp holder;
- ballast starter (driver) enclosed in a plastic case with ventilation holes. Converts alternating current to direct current, contains more powerful capacitors than in the fluorescent lamp ballast circuit. The reason is as follows – the heat generated by the diodes in LED lamps is not directed outward, but inside its body, therefore, ventilation holes in the ballast body are required. The service life of any LED lamp is associated with the number of ventilation holes in the case and the reliability of the capacitors, as well as with zener diodes that equalize the voltage in the event of voltage drops;
- aluminum radiator. Its protruding ribs are located along and in a spiral, which improves heat dissipation;
- the board on which the LEDs are installed. Made of aluminum, on the side facing the radiator, thermal paste is applied, which removes heat – 90% of the heat radiation from the LEDs falls on the aluminum board in which they are installed;
- LEDs, in number from 5, providing the total power of the lamp. The luminous flux generated by them depends on the quality of LEDs;
- light diffuser mounted on an aluminum inner ring. Made of matte plastic, it is used for uniform dispersion of the light beam from LEDs. Practically not heated.
The main elements of an LED lamp are LEDs – semiconductor devices that convert electric current into light radiation. Any LED consists of a non-conductive substrate on which a semiconductor crystal is laid – both of these elements are enclosed in a package with contact leads on one side and a plastic lens on the other side. The free space between the lens and the crystal is filled with colorless silicone, the LED structure is fixed on an aluminum base, which removes heat and makes the LED more rigid.
Why does the LED light up? The secret of the glow lies in the recombination of electrons between two semiconductor contacts with different conductivity. The semiconductor crystal at the points of contact output is doped with an acceptor impurity containing an insufficient number of electrons, on the one hand, and a donor impurity, where electrons are abundant, on the other. When power is applied, electrons recombine and the resulting excess energy is converted into visible light. At first glance, it seems that the higher the current, the more intense the LED will glow. That’s right, the intensity of the light energy will be higher, but at the same time, due to the resistance in the semiconductor, the heating of the diode will sharply increase, which will cause the contacts to melt or the semiconductor burns out.
Pros and cons of energy saving LED bulbs
LED lamps that exist today have both advantages and disadvantages – their development into a full-fledged light source in our homes has not yet been completed..
- the smallest, in comparison with any other types of household lamps, electricity consumption – 8-10 times less than that of lamps with incandescent filament;
- high luminous efficiency, about 120 lumens per watt of energy expended. For comparison, the light output of “Ilyich’s lamps” is from 10 to 24 lumens per watt, for fluorescent lamps – from 60 to 100 lumens per watt;
- the highest, in comparison with any other lighting lamps, service life of about 50,000 hours, provided that the LED lamp itself is of high-quality construction and high-quality materials are used in its manufacture;
- obtaining various characteristics of the spectrum without using light filters, i.e. by analogy with incandescent lamps;
- durability and safety for users. The LED lamp will not break or be damaged if dropped accidentally, i.e. shards of glass, typical for a similar situation with any other lighting lamp, will not be. Its elements do not contain any hazardous components of chemical origin, which are present, for example, in fluorescent lamps;
- does not depend on the number of on and off, in the case of other lamps, the number of on / off seriously affects the service life;
- safe in operation – no high voltage is required, the highest temperature of the LED and enclosing fittings will not exceed 60 ° С.
- high price. The cost of LED lamps today exceeds the cost of fluorescent lamps of similar power by 8-10 times. Reducing retail prices without losing quality is the main challenge for LED lamp manufacturers;
- need for a heat sink. The dimensions of the LEDs are too small and not sufficient to independently dissipate the heat generated by them during operation – the more powerful the LED lamp, the larger the size and area of the radiator it needs. Accordingly, the impressive size of the aluminum radiator affects the cost of the lamp, besides, it will be difficult or impossible to install a powerful LED lamp in ordinary lamps – it will not fit in them;
- in the absence of a capacitor that equalizes the luminous flux of LEDs, there is a noticeable ripple of light;
- when constructing a lamp based on cheap LEDs, its light output decreases to a maximum of 100 lm / W and becomes equal to fluorescent lamps, i.e. an important advantage of the LED lamp is lost;
- the light spectrum generated by LEDs is monochrome and differs significantly from natural sunlight. To soften monochrome light radiation, special phosphors are required;
- the generated luminous flux is narrowly directed and requires the installation of several multidirectional lamps or a light diffuser, however, the use of the latter significantly reduces the illumination intensity.
How to choose an LED lamp for your home
In hardware stores in Russia, energy-saving LED lamps are not as widespread as fluorescent ones – they are more expensive, therefore, they are in less demand. The largest manufacturers of LED lamps: American General Electric, German Osram, Bioledex and BLV licht, Dutch Philips, Indian Sylvania, Russian Optogan – the cost of their products varies from 600 to 3,000 rubles … for one lamp.
In addition to well-known brands, inexpensive LED lamps from Chinese and small domestic manufacturers are often found in stores – in my opinion, you should not buy their products, because the low cost is most likely due to savings on components, which means that such lamps will not last long.
And now about the criteria for choosing LED lamps:
- lamp power. A 100 W incandescent lamp corresponds to a 12-15 W LED, and the luminous flux of a 15 W LED lamp will be slightly more intense than that of a 100 W “Ilyich lamp”;
- light temperature. The temperature of the light in Kelvin will be applied on the package or the lamp body, the sunlight we are used to has a temperature of 2 700 – 3 000 K. The temperature of the light of the lamps in Kelvin owes its origin to the color of the metal bar heated in the oven – up to 3 000 K it is yellow-white , becomes more and more white with increasing temperature. Lamps emitting light at a temperature higher than 3000 K are brighter, but their light is difficult to tolerate and is appropriate only in office premises;
- lighting angle. If all the LEDs in the lamp are located in the same plane, then the nature of the illumination will be focal, narrowly directed – each LED emits a directed luminous flux. For light diffusion and effective lighting of the room, it will be convenient if the LEDs are placed on several planes, and the lamp itself is equipped with light diffusion lenses, coated from the inside with a phosphor;
- color rendering ratio. Its value should be indicated on the lamp packaging, for LEDs, the coefficient is usually from 70 to 95 – the higher the value given on the packaging, the better the LED lamp will shine and vice versa. If the color rendering index of 95 is indicated on the package, and the cost of the lamp itself is low – this is an attempt to deceive the buyer, cheap lamps cannot have such a high color rendering;
- heat removal. The presence of an aluminum radiator is required and if plastic is used instead of aluminum, refuse to buy this lamp, it will not last long;
- working hours. Typically, manufacturers quote 30,000 working hours, which is actually an average. The lamp itself after this period will continue to work, but its brightness will decrease by about 30% – the heating of the LEDs over time reduces the intensity of the luminous flux.
I have no doubt that in the next 5-10 years, LED lamps will be improved – the number of lumens per watt consumed will increase, and the cost will decrease significantly. They will become no less popular, as incandescent lamps once were, only more profitable for both the ordinary consumer and the state. But it will take time …