L12a Solid State Lighting

L12a. Solid State Lighting (SSL)
c. LED Lighting (moved from 12 Other Light Sources)
General Description
An LED (light emitting diode) is an electro-chemical light source. When the diode is forward-biased, light is generated. The light is monochromatic; the colour is dependent on the materials used. White light can be produced by using phosphors similar to those used in fluorescent and coated HID lamps.
Efficacy
The efficacy of LED sources is improving continuously; currently about 30 lm/W is typical.
Life
Lamp lumen depreciation in a light source is the gradual reduction in light output over time, caused by normal deterioration of phosphors, cathodes, filaments and the other components of the system. LED systems last up to 100,000 hours, based on the fact that when the light output has depreciated to less than 50% of initial output, then the light source has effectively expired. Life of LED systems is dependent on a number of factors including the colour; red and green LEDs last significantly longer than blue and white LEDs.
Advantages
• Low power consumption and low heat generation.
• Extremely long life.
• Negligible early failures.
• High colour efficiency, because they are monochromatic.
• Very small.
• Resistant to damage from shock and vibration.
• No infra-red or ultra-violet energy is emitted.
Applications
• Typically used in exposed source applications such as signage, decorative festive lighting, marketing displays, and automotive applications
• Traffic signal lamps
• Exit signs
• Seasonal light strings

White Light LEDs (Moved from 14 Emerging Technologies)
• The LED segment of the market is growing and is believed to be the technology of the future for lighting; efficient, long-life white light LEDs in convenient packages, such as a medium screw base lamp module, could replace traditional incandescent lamps.