Normal incandescent bulbs- contained within the very thin glass of this type of bulb is an inert gas such as argon or nitrogen. Electricity is passed across the tungsten filament in the centre of the bulb, which heats the filament up to around 2,500°C. The filament becomes ‘white hot’ and gives off light – incandescence. Because normal light bulbs radiate a large amount of infrared heat (wasted energy), they are not very efficient and often only last between 800 and 1000 hours in normal use. Eventually the tungsten filament evaporates, breaks and the bulb ‘burns out’.
Fluorescent tubes – glass tubes with metal fittings on each end through which electricity is passed. Inside the glass tube is a small amount of magnesium and an inert gas (a gas which does not normally react to stimulation such as heat or electricity), usually argon. The inside of the tube is coated in a phosphorous powder. When electricity is passes through, magnesium atoms release energy in the form of ultraviolet light. Ultraviolet light is normally invisible to the naked eye, but in contact with the phosphorous coating causes the phosphorous begins glow, creating light.
LED lighting utilises high efficiency silicon substrates known as Light Emitting Diodes (LED’s) which glow when current passes through them, resulting in light.
Halogen lamps also use a tungsten filaments, but enclosed inside a much smaller quartz bulb to enable it to be much closer to the filament than normal glass. When the halogen gas inside the lamp is combined with tungsten vapour at a high enough temperature, tungsten atoms are evaporated and redeposited on the filament. This allows the filament to be recycled and therefore last longer. However because the quartz glass is so close to the filament halogen lamps get extremely hot.
Light Emitting Diodes do not produce any heat, ultraviolet or infrared radiation; almost all of the energy supplied to a LED chip is converted to light using only a fraction of the energy of normal bulbs, halogen or fluorescents.
These 4 parts make up an LED luminaire:-
LED chip(s) that produces the light
Control gear (if 240V)
The lifespan of an LED luminaire will depend on the design, engineering and the quality of each of these components.
Maintaining temperature is one of the most important factors that affect the life span of an LED chip. This is why LED lights normally contain a heat sink; a large surface area which helps remove heat produced by the LED chip while turned on. The heat sink helps maintain the temperature of the LED chips to allow the LED chip to last its expected lifespan. Good quality LED luminaires have correctly sized heat sinks enabling LED chips to maintain temperature – the more powerful the LED light, the bigger the heat sink required. However, poorly manufactured LED lights often have incorrectly sized heat sinks to reduce production costs savings by using less material. This results in a reduced lifespan of the LED luminaire.
LED chips only require small voltages to light up, i.e. 12V, 24V and so on. Some LED lights are designed to run off a 240V supply. Because of this, 240V LED lights contain inbuilt or external power supplies that convert 240V to lower voltages. The quality of voltage and current produced by these power supplies will also greatly determine the life span of the LED chip. A chip manufacturer will specify the necessary power supply requirements to allow it to last its designed life span. The manufacturer of the LED light designs and selects a suitable power supply that can meet this demand which must be able to effectively regulate the current supplied to the LED chip. Cheap LED lights often use cheap power supplies in order to cut costs. The manufacturer may specify the LED light uses quality CREE chips but they might use poor quality power supplies which ends up degrading the overall lifespan of the product. Poor quality power supplies often fail even before the LED chip fails- a limiting factor in the LED light’s life span.
Finally, the quality of LED light depends on the quality of the LED chip itself. We use quality LED chip manufacturers, Bridgelux and Epistar. Remember, choose a well-known lighting manufacturer and your LED lights will last much longer!