There are several reasons that guide us in choosing a light bulb. Its power, its consumption, its form, its technology … The LED bulbs pierce more and more in the life of every day. They have many advantages: the size, the multiplicity of colors, the very low consumption, the good yield. They still have defects that tend to resolve: a very direct light, a comparatively low intensity, not to mention the cost of acquisition which can be prohibitive despite the fact that it is an old technology. What is a LED?
LED is an English word for “light emitting diode” which means “light emitting diode”. The acronym francophone would be DEL.
The LED is an opto-electronic component. This simply means that it is an electronic component capable of emitting light when it is traversed by an electric current. An electroluminescent diode only passes the electrical current in only one direction-from the anode to the cathode (the direction passing, like a conventional diode, the reverse being the blocking direction) and it produces incoherent monochromatic or polychromatic radiation From the conversion of electrical energy when a current passes through it.
On the electronic diagrams you can spot it thanks to its characteristic symbol: it is that of a classic diode surmounted by two arrows. The latter symbolize the emission of photons (of light). Some variants exist in this representation.
The paternity of the diodes is granted to Nick Holonyak Jr. He was the first to create a light-emitting diode with visible spectrum in 1962. For a long time, the researchers thought it necessary to limit themselves to the three colors: red, yellow and green.
It was only in 1990 that the blue diode was developed by Dr. Shuji Nakamura, then employed by the company (en) Nichia. The white LED has therefore been able to be developed by the coupled use of blue LED and yellow phosphor. This was the starting point for major new applications: lighting, TV screens and computers.
LEDs can browse the color spectrum, whether they are visible (colors, white) or invisible (infrared, ultraviolet).
The color of a light-emitting diode can be generated in different ways:
- Coloration due to the wavelength of the semiconductor (transparent cover);
- Coloration modified by the cover of the diode (blue emission or UV + coating based on luminophores);
- Coloration by several different wavelength emissions: polychromatic light-emitting diodes.In particular, they offer a wide range of colors
For white, we do not speak of wavelength but of color temperature (expressed in Kelvin – K). That of the light-emitting diodes is quite variable depending on the model.
To appreciate this measurement here are some examples of different color temperatures:
- Sun on the horizon 2 000 K
- Sodium lamp 2 200 K
- Incandescent lamp 2,400-2,700 K
- Fluorescent lamp warm white 2,700 to 3,000 K
- Metal halide lamps 3,000 to 4,200 K
- Halogen lamp 3,000 to 3,200 K
- Fluorescent white fluorescent lamp 3 900 to 4 200 K
- Sun at the zenith 5 800 K
- Daylight fluorescent lamp 5 400 to 6 100 K
- Natural light standard 5 000 K (D50) or 6 500 K (D65)
Two types of diodes can be distinguished by their power:
- The light emitting diodes of low power <1 W: they are the most widespread and are used for indicator lights for example.
- High power LEDs> 1W: more recent they are booming.They are used in laptop flash, lighting
Since their invention in 1962, LEDs have continued to evolve: their luminous flux has doubled every 18 to 24 months for 30 years.
To obtain a bulb having a luminous output equivalent to conventional bulbs, it was necessary to assemble a good number of LEDs on a same support, both to obtain a luminous intensity usable in the context of domestic lighting, and to obtain a dispersion angle of The widest possible light in order to get closer to the 360 ° of the incandescent bulbs. Today with technological advances the bulbs require less LED and can gain in clutter.
LEDs hardly heat up and their consumption is very low their lifespan range from 50,000 to 100,000 hours.
In summary, the advantages of LEDs are:
- low consumption,
- Available in several colors,
- Low or no heating,
- Small footprint,
- Reliability: high resistance to shocks, vibrations and crushing,
- Insensitive to repeated ignition
- Long lifespan
- Instantaneous ignition
Some important points to know
- The LEDs can not operate with a conventional dimmer.
TRUE and FALSE: The standard for light bulbs put on a lamp powered by alternating current that is true. On the other hand, there are LED bulbs that are compatible with dimmers. These bulbs embed electronics to allow this variation in light intensity.
- Never look at a LED bulb in the front, you risk temporary blindness.
TRUE: The LED light is very Director, the flow (especially that of the blue light) is concentrated and can be harmful notemment in children who have a retina sensitive than adults.
- LEDs have a long service life
TRUE: LEDs have a lifespan of over 25 years as part of a household use. Unlike other bulbs, the LEDs do not leave overnight (except for the problem of electronics) but their intensity decreases as and when.
- The more LEDs in a light bulb, the more bright it is.
FALSE: It would be too easy. A single very powerful LED is better than 50 weak points. So it’s not a criterion of choice. It all depends on the manufacturing technology of the LED used.
- SMD LEDs are better than others.
FALSE: This is simply a more modern manufacturing technology. SMD stands for “Surface mounted device”, and in French CMS stands for “Surface mounted component”. The component is directly welded to the front face of the printed circuit board, so there is no welding on the external face of the printed circuit since the pins of the LED do not pass through the printed circuit. This makes it possible to reduce manufacturing costs but above all brings a fineness in thickness of the products designed. The angle of diffusion is generally quite wide. In return this type of LED heats more than a classic LED.
Whether LED welds are made on one side or the other of the printed circuit will not change much to their luminous power.
Want to read more about LED? Click here: bestitude.com.
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