Tuesday, November 11, 2008
Sunday, November 2, 2008
LED Lighting Applications
LED Lighting Applications
Flashlights and lanterns that utilize white LEDs are becoming increasingly popular because of their durability and longer battery life.
White LED module
Replacement light bulbs
Flashlights with low energy usage and high durability
Lanterns
Streetlights
Large scale video displays
Architectural lighting
Light source for machine vision systems, requiring bright, focused, homogeneous and possibly strobed illumination.
Vehicle lighting on cars, motorcycles and bicycle lights
Backlighting for LCD televisions and lightweight laptop displays.
Light source for DLP projectors
Stage lights using banks of RGB LEDs to easily change color and decrease heating from traditional stage lighting.
Medical lighting where IR-radiation and high temperatures are unwanted.
Strobe lights or camera flashes that operate at a safe, low voltage, as opposed to the 250+ volts commonly found in xenon flashlamp-based lighting. This is particularly applicable to cameras on mobile phones, where space is at a premium an bulky voltage-increasing circuitry is undesirable.
Flashlights and lanterns that utilize white LEDs are becoming increasingly popular because of their durability and longer battery life.
White LED module
Replacement light bulbs
Flashlights with low energy usage and high durability
Lanterns
Streetlights
Large scale video displays
Architectural lighting
Light source for machine vision systems, requiring bright, focused, homogeneous and possibly strobed illumination.
Vehicle lighting on cars, motorcycles and bicycle lights
Backlighting for LCD televisions and lightweight laptop displays.
Light source for DLP projectors
Stage lights using banks of RGB LEDs to easily change color and decrease heating from traditional stage lighting.
Medical lighting where IR-radiation and high temperatures are unwanted.
Strobe lights or camera flashes that operate at a safe, low voltage, as opposed to the 250+ volts commonly found in xenon flashlamp-based lighting. This is particularly applicable to cameras on mobile phones, where space is at a premium an bulky voltage-increasing circuitry is undesirable.
Advantages of Using LEDs
Advantages of using LEDs
Efficiency: LEDs produce more light per watt than incandescent bulbs; this is useful in battery powered or energy-saving devices.
Color: LEDs can emit light of an intended color without the use of color filters that traditional lighting methods require. This is more efficient and can lower initial costs.
Size: LEDs can be very small (>2 mm2) and are easily populated onto printed circuit boards.
On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds. LEDs used in communications devices can have even faster response times.
Cycling: LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.
Dimming: LEDs can very easily be dimmed either by Pulse-width modulation or lowering the forward current.
Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.
Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life, though time to complete failure may be longer.
Shock resistance: LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.
Focus: The solid package of the LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.
Toxicity: LEDs do not contain mercury, unlike fluorescent lamps.
Efficiency: LEDs produce more light per watt than incandescent bulbs; this is useful in battery powered or energy-saving devices.
Color: LEDs can emit light of an intended color without the use of color filters that traditional lighting methods require. This is more efficient and can lower initial costs.
Size: LEDs can be very small (>2 mm2) and are easily populated onto printed circuit boards.
On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds. LEDs used in communications devices can have even faster response times.
Cycling: LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.
Dimming: LEDs can very easily be dimmed either by Pulse-width modulation or lowering the forward current.
Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.
Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life, though time to complete failure may be longer.
Shock resistance: LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.
Focus: The solid package of the LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.
Toxicity: LEDs do not contain mercury, unlike fluorescent lamps.
LED Advantages
While all diodes release light, most don't do it very effectively. In an ordinary diode, the semiconductor material itself ends up absorbing a lot of the light energy. LEDs are specially constructed to release a large number of photons outward. Additionally, they are housed in a plastic bulb that concentrates the light in a particular direction. As you can see in the diagram, most of the light from the diode bounces off the sides of the bulb, traveling on through the rounded end.
LEDs have several advantages over conventional incandescent lamps. For one thing, they don't have a filament that will burn out, so they last much longer. Additionally, their small plastic bulb makes them a lot more durable. They also fit more easily into modern electronic circuits.
But the main advantage is efficiency.
While all diodes release light, most don't do it very effectively. In an ordinary diode, the semiconductor material itself ends up absorbing a lot of the light energy. LEDs are specially constructed to release a large number of photons outward. Additionally, they are housed in a plastic bulb that concentrates the light in a particular direction. As you can see in the diagram, most of the light from the diode bounces off the sides of the bulb, traveling on through the rounded end.
LEDs have several advantages over conventional incandescent lamps. For one thing, they don't have a filament that will burn out, so they last much longer. Additionally, their small plastic bulb makes them a lot more durable. They also fit more easily into modern electronic circuits.
But the main advantage is efficiency.
In conventional incandescent bulbs, the light-production process involves generating a lot of heat (the filament must be warmed). This is completely wasted energy, unless you're using the lamp as a heater, because a huge portion of the available electricity isn't going toward producing visible light. LEDs generate very little heat, relatively speaking. A much higher percentage of the electrical power is going directly to generating light, which cuts down on the electricity demands considerably.
Up until recently, LEDs were too expensive to use for most lighting applications because they're built around advanced semiconductor material. The price of semiconductor devices has plummeted over the past decade, however, making LEDs a more cost-effective lighting option for a wide range of situations.
While they may be more expensive than incandescent lights up front, their lower cost in the long run can make them a better buy. In the future, they will play an even bigger role in the world of technology.
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