An LED lamp or LED light bulb is an electric light that produces light using light-emitting diodes (LEDs). LED lamps are significantly more energy-efficient than equivalent incandescent lamps and can be significantly more efficient than most fluorescent lamps. The most efficient commercially available LED lamps have efficiencies of 200 lumen per watt (Lm/W). Commercial LED lamps have a lifespan many times longer than incandescent lamps.
Pritish Kumar Halder shares the LED diode led electrical bulb making process.
LED lamps to require an electronic LED driver circuit to operate from mains power lines, and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The driver circuit may require special features to be compatible with lamp dimmers intended for use on incandescent lamps. Generally, the current waveform contains some amount of distortion, depending on the luminaires’ technology.
White light LEDs
General-purpose lighting requires a white light, emulating a black body at a specified temperature, from “warm white” (like an incandescent bulb) at 2700K, to “daylight” at around 6000K. The first LEDs emitted light in a very narrow band of wavelengths, of a color characteristic of the energy band gap of the semiconductor material used to make the LED.
LEDs that emit white light are made using two principal methods: either mixing light from multiple LEDs of various colors, or using a phosphor to convert some of the light to other colors. The light is not the same as a true black body, giving a different appearance to colors than an incandescent bulb. Color rendering quality is specified by the CRI, and as of 2019 is about 80 for many LED bulbs, and over 95 for more expensive high-CRI LED lighting (100 is the ideal value).
Color changing LED lighting
Tunable lighting systems employ banks of colored LEDs that can be individually controlled, either using separate banks of each color, or multi-chip LEDs with the colors combined and controlled at the chip level. For example, white LEDs of different color temperatures can be combined to construct an LED bulb that decreases its color temperature when dimmed.
LED chips require controlled direct current (DC) electrical power and an appropriate circuit as an LED driver is required to convert the alternating current from the power supply to the regulated voltage direct current used by the LEDs.
LED drivers are essential components of LED lamps to ensure acceptable lifetime and performance of the lamp. A driver can provide features such as dimming and remote control. It drivers may be in the same lamp enclosure as the diode array, or remotely mounted from the light-emitting diodes. LED drivers may require additional components to meet regulations for acceptable AC line harmonic current.
High temperature of LEDs can cause premature failure and reduced light output. LED lamps tend to run cooler than their predecessors since there is no electric arc or tungsten filament, but they can still cause burns. Thermal management of high-power LEDs is required to keep the junction temperature of the LED device close to ambient temperature, since increased temperature will cause increased current, more heating, more current, and so on until failure. LEDs use much less power for a given light output, but they do produce some heat, and it is concentrated in a very small semiconductor die, which must be cooled.
LED lamps typically include heat sinks and cooling fins. Very high-power lamps for industrial uses are frequently equipped with cooling fans. Some place the LEDs and all circuitry in a glass bulb just like conventional incandescent bulbs, but with a helium gas filling to conduct heat and thus cool the LEDs. Others place the LEDs on a circuit board with an aluminum backing; the aluminum back is connected thermally to the aluminum base of the lamp using thermal paste, and the base is embedded in a melamine plastic shell.
LED lamps are used for both general and special-purpose lighting. Where colored light is needed, LEDs that inherently emit light of a single color require no energy-absorbing filters. This lamps are commonly available as drop-in replacements for either bulbs or fixtures, replacing either an entire fixture or bulbs.
Household LED lamps
Sizes and bases
LED lamps are made with standard lamp connections and shapes, such as an Edison screw base, an MR16 shape with a bi-pin base, or a GU5.3 (bi-pin cap) or GU10 (bayonet fitting) and are made compatible with the voltage supplied to the sockets. They include driver circuitry to rectify the AC power and convert the voltage to an appropriate value, usually a switched-mode power supply.
LED tube lamps
LED tube lights are designed to physically fit in fixtures intended for fluorescent tubes. Some LED tubular lamps are intended to be a drop-in replacement into existing fixtures if appropriate ballast is used. Others require rewiring of the fixtures to remove the ballast. An LED tube lamp generally uses many individual Surface-Mounted LEDs which are directional and require proper orientation during installation as opposed to fluorescent tube lamps which emit light in all directions around the tube. Most LED tube lights available can be used in place of T5, T8, T10, or T12 tube designations, T8 is D26mm, T10 is D30mm, in lengths of 590 mm (23 in), 1,200 mm (47 in) and 1,500 mm (59 in).
Lighting designed for LEDs
Newer light fittings with long-lived LEDs built-in, or designed for LED lamps, have been coming into use as the need for compatibility with existing fittings diminishes. Such lighting does not require each bulb to contain circuitry to operate from mains voltage.
Experiments revealed surprising performance and production of vegetables and ornamental plants under LED light sources. Many plant species have been assessed in greenhouse trials to make sure that the quality of biomass and biochemical ingredients of such plants is at least comparable with those grown in field conditions
Plant performance of mint, basil, lentil, lettuce, cabbage, parsley and carrot was measured by assessing both the health and vigor of the plants and the success of the LEDs in promoting growth. Also noticed was profuse flowering of select ornamentals including primula, marigold and stock.
Light emitting diodes (LEDs) offer efficient electric lighting in desired wavelengths (red + blue) which support greenhouse production in minimum time and with high quality and quantity. As LEDs are cool, plants can be placed very close to light sources without overheating or scorching, requiring much less space for intense cultivation than with hot-running lighting.
LEDs are increasingly used for street lighting in place of mercury and sodium lamps due to their lower running and lamp replacement costs. However, there have been concerns that the use of LED street lighting with predominantly blue light can cause eye damage, and that some LEDs switch on and off at twice mains frequency, causing malaise in some people, and possibly being misleading with rotating machinery due to stroboscopic effects. These concerns can be addressed by use of appropriate lighting, rather than simple concern with cost.