22-03-2011, 02:06 PM
Presented By
S V PRAMOD
M SUNIL KUMAR REDDY
2030.ppt (Size: 2.97 MB / Downloads: 70)
WHAT IS A LED
Solid state semiconductor device.
Releases energy in the form of photons.
ELECTROLUMINESCENCE.
Refractive Indices.
E=qV (joules)
TYPES OF LED
WHITE LEDs
PHOTONIC LATTICE
ORGANIC LEDs
MINIATURE LEDs
HIGH POWER LEDs
SUPER FLUX LEDs
ALPHANUMERIC LEDs
RADIATION PATTERN AND VISIBILTY CONSIDERATIONS
LEDS ARE HIGHLY DIRECTIONAL
LED's luminous intensity is half the intensity at direct on-axis view
luminous efficiency in the range of 85-90%.
CONSIDERATIONS FOR USE
POWER SOURCES
LEDs USING SOLAR
ENERGY
ELECTRICAL POLARITY
SAFETY
SOME BASIC FACTS ABOUT LEDS
• White LEDs can be placed in abusive environments.
• White LEDs can be "AC" or "DC" powered depending on the model.
• White LEDs are the newest lighting device on the market today.
• White LEDs do not produce "RF" to interfere with radio equipment.
• White LEDs are a proven technology.
• White LEDs last about 100, 000 hours of continuous use.
• White LEDs radiate light at a 15 to 45 degree angle depending on the model.
• White LEDs can be made completely waterproof for use in many marine applications.
• White LEDs are polarity protected, so it is hard to make an installation mistake.
HOW LED LIGHTING SYSTEM IS BETTER THAN CONVENTIONAL LIGHTING SOURCES
EFFICIENCY
COLOUR
SIZE
DIMMING
LIFETIME
SHOCK RESISTANCE
TOXICITY
LUMINOUS EFFICACY:
The efficiency of a device in converting electrical power into visible light is called luminous efficacy or luminous performance. It is measured in (lm/W).