Light Emitting Diodes
Light emitting diodes are the light source in an LED flashlight. Because of their size and capability, they are used in promotional items (especially those that blink), traffic lights, overhead office lighting, and signs. Flashlights and other hand-held items are a great place to use diodes because of the LEDs' durability and the increase in the life of the batteries. LEDs work because of the diode--a semiconductor electronic component that contains two electrodes, also called terminals, that generate light when electricity runs through them. Each diode contains a semiconductor chip and a reflective cup and are housed in a clear or colored epoxy. They attach to a socket via two terminals, one anode (flowing into) and the other cathode (flowing out of). LED flashlights are flashlights that have replaced the traditional bulb with a light emitting diode.
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Using LED Flashlights
LEDs found in average hand-held flashlights are housed in a parabolic reflective cavity covered with a clear lens to protect the diode. The power source for lighting the diode is a required series of batteries. The diode and the batteries are separated by a switch. The whole mechanism, batteries and switch are housed in a tube or appropriate housing for the batteries required. This closed circuit charges the diode when the switch is turned to the on position, therefore allowing the current to travel through the LED. The light produced is bright, clear and intense and is bounced off the reflective cavity, through the lens and out into the surrounding area. A lens controls the area the light can spread across and will direct the beam to fill a wide or narrow area.
Advantages And Disadvantages
There are many advantages to using an LED light source. LEDs last longer, are more reliable and use much less energy. Because they are housed in a plastic coating, they are much sturdier and respond to being dropped or abused without breaking like an incandescent bulb might. Because they operate at such low temperatures, their shelf life is many times more than a traditional bulb. Turning them on and off causes minimal wear and tear. One of the disadvantages is susceptibility to damage by static electricity. More importantly, the intensity of an LED can cause eye damage if looked at directly by unprotected eyes. Never stare directly into an LED flashlight.