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Light Emitting Diodes are a luminous source based on semiconductor diodes.
When the diode is lit up, electrons can recombine with the gaps inside the diode, releasing energy as photons: this effect is called electroluminescence. LED sources bring many advantages over incandescent sources:
- greater duration: LED lamps last about 10 times more than HID lamps. Producers declare LEDs’ life in the values of 50,000 or 100,000 hours. The light emission is constant around 30,000 hours; afterwards there is a reduction in the light emission. In fact LEDs burn out growing dim during time, while incandescent lamps burn out all of a sudden without prior warning.
- low consumption.
- small size.
- resistance to shocks: LED lamps do not contain tube lamps that can be broken, and their inner parts are fixed, making them more resistant than discharge lamps to vibrations and impacts (discharge lamps are more fragile, especially when hot).
- cold light: LED lamps emit very little heat as IR beams and UV beams. The dispersed energy is dissipated as heat.
- reduction of maintenance costs: although LED lamps are more expensive than traditional ones, such choice is more convenient in the long run, because this investment is completely paid off due to higher efficiency, savings in terms of reduced consumption and lack of necessity of light bulbs substitution.
- toxicity: LED lamps do not contain mercury (while HMI lamps do).
- cycle: LED lamps are ideal in applications that demand many switching on/off cycles, for flash effects impossible to get with HID lamps (that require much time before relighting).
- dimming: thanks to the LED lamps electronic circuit, the lamp can be easily dimmed with no need of an external dimmer, giving spectacular fade-in/fade-out effects.
LED efficiency diminishes as temperature grows, which limits the watts that can be used in the lamps production. In LEDs, a fraction of the electricity is transformed in heat rather than in light. If this heat is not removed, the LED works at a temperature higher than normal, which reduces its efficiency and reliability. For this reason, heat dissipation is a factor of higher importance in LEDs than in traditional luminous sources: because LEDs produce some heat, even if it is minimal, it is nonetheless necessary to take a good care when designing the projector installation. |
