LED Light Bulbs
LED Light Bulbs (LEDs) are Light Emitting Diodes. These are a relatively old technology, dating from the 70s. The effect was first discovered in 1907, but no practical use was seen for the technology at the time. We are used to them in digital readouts like those in digital watches, but probably don’t realize they are also becoming increasingly common in traffic lights, torches, automobile lamps and in signs, such as exit signs.
LED Light Bulbs are small (about 5mm), use little power and produce little heat although they don’t react well to overcharging. LED Light Bulbs have a long lifespan and are relatively rugged, for lights. LED Light Bulbs are solid-state semiconductor devices, with no moving parts to break. Power is fed into the diodes, resulting in negatively charged electrons in one layer of the diode, and ions lacking electrons, and thus positively charged, in another layer. The energy released when these meet becomes light. The material of the diode can also produce colored light, with white, deep blue, blue, green, yellow, amber, orange, red, bright red and deep red possible. They can produce a ratio of lumens, a measurement of light, to watts, a measurement of power, greater than incandescent bulbs and rivaling fluorescents. In 1993 it took 200 LEDs to replace an incandescent bulb. Today it takes 18, and 10 is the goal.
The LED Light Bulbs replacement for the lights in a traffic light have 196 LEDs, and draw one fifteenth the current as the conventional bulb. Since traffic lights are on around half the time, this translates to perhaps a 35% saving. LED replacement bulbs have a potential energy saving of over 80-90% as the technology continues to mature. For this reason the technology is well suited to use in LED torches. The theoretical lifespan is up to 1,000,000 hours. LED Light Bulbs are not prone to failure through repeatedly being switched on and off. This makes LEDS advantageous in applications such as blinking LED status lights and indicator lights in the automotive industry.
The light produced from LED Light Bulbs is not competitive for all uses. For instance, it can subtly change the appearance of items lit by the lights, and so isn’t suitable for painters or photographers. The wide variety of choices available, when compared with incandescent lights, simply isn’t there yet for LED Light Bulbs. Also, without limited standardization, some worry that parts may be difficult to obtain as systems get older, and might thus need to be entirely replaced. LED light bulbs focus light into a smaller area than other lights of comparable lumen ratings.
In terms of lifespan, LED Light Bulbs are expected to last from 100,000 hours. Fluorescent bulbs should last about 10,000 hours, and incandescent bulbs 1,000 hours. LED’s cost far more to purchase than other types of lights, though the low cost of operation makes them competitive with fluorescents and much cheaper than incandescent lights. Since a single LED can replace perhaps 40 incandescent bulbs over its lifespan, the high cost of each bulb isn’t as severe. Add in the electrical savings and the system looks very attractive. Since fluorescent bulbs need to be bagged and treated as hazardous waste, like batteries, LEDs have another theoretical advantage. Fluorescents also have a minor strobe effect that can cause some people to react poorly or even become ill in rare cases. While cases can be made for other types of lighting, LED Light Bulbs are competitive and getting better.