Advantages:-
1.Efficiency:-
LEDs emit more lumens per watt than incandescent light bulbs. The efficiency of LED lighting fixtures is not affected by shape and size , unlike fluorescent light bulbs or tubes.
2.Color:-
LEDs can emit light of an intended color without using any color filters as traditional lighting methods need. This is more efficient and can lower initial costs.
3.Size:-
LEDs can be very small and are easily attached to printed circuit boards.
4.On/off TIME:-
LEDs light up very quickly. A typical red indicator LED will achieve full brightness in under a microsecond. LEDs used in communications devices can have even faster response times.
5.Cycling:-
LEDs are ideal for uses subject to frequent on-off cycling, unlike fluorescent lamps that fail faster when cycled often, or HID lamps that require a long time before restarting.
6.Dimming:-
LEDs can very easily be dimmed either by pulse-width modulation or lowering the forward current. This pulse-width modulation is why LED lights viewed on camera, particularly headlights on cars, appear to be flashing or flickering. This is a type of stroboscopic effect.
7.Cool Light:-
In contrast to most light sources , LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED.
8.Slow Failure:-
LEDs mostly fail by dimming over time, rather than the abrupt failure of incandescent bulbs.
9.Shock Resistance:-
LEDs being solid-state components , are difficult to damage with external shock, unlike fluorescent and incandescent bulbs, which are fragile.
10.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. For large LED packages total internal reflection (TIR) lenses are often used to the same effect.
Disadvantages:-
1.High Initial Price:-
LEDs are currently more expensive , price per lumen, on an initial capital cost basis , than most conventional lighting technologies. The additional expense partially systems from the relatively low lumen output and the drive circuitry and power supplies needed.
2.Temperature Dependence:-
LED performance largely depends on the ambient temperature of the operating environment or thermal management properties. Over driving an LED in high ambient temperatures may result in overheating the LED package , eventually leading to device failure.
3.Voltage Sensitivity:-
LEDs must be supplied with the voltage above the threshold and a current below the rating .This can involve series resistors or current regulated power supplies.
4.light Quality:-
Most cool white LEDs have spectra that differ significantly from a black body radiator like the sun or an incandescent light. However , the color rendering properties of common fluorescent lamps are often inferior to what is now available in state of art white LEDs.
5.Area Light Source:-
Single LEDs do not approximate a point source of light giving a spherical light distribution , but rather a lambertian distribution. So LEDs are difficult to apply to uses needing a spherical light field , however different fields of light can be manipulated by the application of different optics or lenses.
6.Electrical polarity:-
Unlike incandescent light bulbs, which illuminate regardless of the electrical polarity LEDs will only light with correct electrical polarity.
7.Blue Pollution:-
Because cool white LEDs with high color temperature emit proportionally more blue light than conventional outdoor light sources such as high- pressure sodium vapor lamps, the strong wavelength dependence of Rayleigh scattering means that cool white LEDs can cause more light pollution than other light sources.
8.Blue Hazard:-
There is concern that blue LEDs and cool white LEDs are now capable of exceeding safe limits of the so called blue - light hazard as defined in eye safety specification such as ANSI/IESNA RP-27.1-05: recommended practice for Photobiological safety for lamp and lamp Systems.
9.Efficiency Droop:-
The luminous efficacy of LEDs decreases as the electrical current increases. Heating also increases with higher currents which compromises the lifetime of the LED. These effects put practical limits on the current through an LED in high power applications.
1.Efficiency:-
LEDs emit more lumens per watt than incandescent light bulbs. The efficiency of LED lighting fixtures is not affected by shape and size , unlike fluorescent light bulbs or tubes.
2.Color:-
LEDs can emit light of an intended color without using any color filters as traditional lighting methods need. This is more efficient and can lower initial costs.
3.Size:-
LEDs can be very small and are easily attached to printed circuit boards.
4.On/off TIME:-
LEDs light up very quickly. A typical red indicator LED will achieve full brightness in under a microsecond. LEDs used in communications devices can have even faster response times.
5.Cycling:-
LEDs are ideal for uses subject to frequent on-off cycling, unlike fluorescent lamps that fail faster when cycled often, or HID lamps that require a long time before restarting.
6.Dimming:-
LEDs can very easily be dimmed either by pulse-width modulation or lowering the forward current. This pulse-width modulation is why LED lights viewed on camera, particularly headlights on cars, appear to be flashing or flickering. This is a type of stroboscopic effect.
7.Cool Light:-
In contrast to most light sources , LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED.
8.Slow Failure:-
LEDs mostly fail by dimming over time, rather than the abrupt failure of incandescent bulbs.
9.Shock Resistance:-
LEDs being solid-state components , are difficult to damage with external shock, unlike fluorescent and incandescent bulbs, which are fragile.
10.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. For large LED packages total internal reflection (TIR) lenses are often used to the same effect.
Disadvantages:-
1.High Initial Price:-
LEDs are currently more expensive , price per lumen, on an initial capital cost basis , than most conventional lighting technologies. The additional expense partially systems from the relatively low lumen output and the drive circuitry and power supplies needed.
2.Temperature Dependence:-
LED performance largely depends on the ambient temperature of the operating environment or thermal management properties. Over driving an LED in high ambient temperatures may result in overheating the LED package , eventually leading to device failure.
3.Voltage Sensitivity:-
LEDs must be supplied with the voltage above the threshold and a current below the rating .This can involve series resistors or current regulated power supplies.
4.light Quality:-
Most cool white LEDs have spectra that differ significantly from a black body radiator like the sun or an incandescent light. However , the color rendering properties of common fluorescent lamps are often inferior to what is now available in state of art white LEDs.
5.Area Light Source:-
Single LEDs do not approximate a point source of light giving a spherical light distribution , but rather a lambertian distribution. So LEDs are difficult to apply to uses needing a spherical light field , however different fields of light can be manipulated by the application of different optics or lenses.
6.Electrical polarity:-
Unlike incandescent light bulbs, which illuminate regardless of the electrical polarity LEDs will only light with correct electrical polarity.
7.Blue Pollution:-
Because cool white LEDs with high color temperature emit proportionally more blue light than conventional outdoor light sources such as high- pressure sodium vapor lamps, the strong wavelength dependence of Rayleigh scattering means that cool white LEDs can cause more light pollution than other light sources.
8.Blue Hazard:-
There is concern that blue LEDs and cool white LEDs are now capable of exceeding safe limits of the so called blue - light hazard as defined in eye safety specification such as ANSI/IESNA RP-27.1-05: recommended practice for Photobiological safety for lamp and lamp Systems.
9.Efficiency Droop:-
The luminous efficacy of LEDs decreases as the electrical current increases. Heating also increases with higher currents which compromises the lifetime of the LED. These effects put practical limits on the current through an LED in high power applications.
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