Advantages of using LED

Disadvantages of using LED

LED produce more light per watt than incandescent bulbs; this is useful in battery powered or energy-saving devices

LED are currently more expensive, price per lumen, on an initial capital cost basis, than more conventional lighting technologies. The additional expense partially stems from the relatively low lumen output and the drive circuitry and power supplies needed. However, when considering the total cost of ownership (including energy and maintenance costs), LED far surpass incandescent or halogen sources and begin to threaten compact fluorescent lamps

LED 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.

LED performance largely depends on the ambient temperature of the operating environment. Over-driving the LED in high ambient temperatures may result in overheating of the LED package, eventually leading to device failure. Adequate heat-sinking is required to maintain long life. This is especially important when considering automotive, medical, and military applications where the device must operate over a large range of temperatures, and is required to have a low failure rate.

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

LED 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

LED 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.

The spectrum of some white LED differs significantly from a black body radiator, such as the sun or an incandescent light. The spike at 460 nm and dip at 500 nm can cause the color of objects to be perceived differently under LED illumination than sunlight or incandescent sources, due to mesmerism Color rendering properties of common fluorescent lamps are often inferior to what is now available in state-of-art white LED

LED can very easily be dimmed either by Pulse-width modulation or lowering the forward current.

LED do not approximate a “point source” of light, so cannot be used in applications needing a highly collimated beam. LED are not capable of providing divergence below a few degrees. This is contrasted with lasers, which can produce beams with divergences of 0.2 degrees or less

LED light up very quickly. A typical red indicator LED will achieve full brightness in microseconds LED used in communications devices can have even faster response times.

There is increasing concern that blue LED and white LED are now capable of exceeding safe limits of the so-called blue-light hazard as defined in eye safety specifications such as ANSI/IESNA RP-27.1-05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems

LED mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs

LED 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. Fluorescent tubes typically are rated at about 30,000 hours, and incandescent light bulbs at 1,000–2,000 hours

LED, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile

LED can be very small and are easily populated onto printed circuit boards.

LED do not contain mercury, unlike compact fluorescent lamps

Due to the human eye's visual persistence LED can be pulse width or duty cycle modulated in order to save power or achieve an apparent higher brightness for a given power input. The eye will tend to perceive the peak current light level rather than the average current light level when the modulation rate is higher than approximately 1000 hertz and the duty cycle is greater than 15 to 20%^, This is also useful when applied to the multiplexing used in 7-segment displays