Components of a LED Light Bulb and how an LED Light Bulb Works
A Light Emitting Diode or LED is connected to an electrical circuit by two conducing leads, the cathode and anode. The cathode is connected to the negative side of the circuit, while the anode is connected to the positive side. The flat spot in the case signifies which lead of the LED represents the cathode. If the cathode and anode are connected the wrong way, the LED will not light up.
Inside the LED, a semiconductor die is connected to the cathode, and placed on a widened part of the cathode called the anvil. A very thin wire bonds the other side of the semiconductor to the anode. Inside the LED the anode is also called the post. The anvil and post together are known as the leadframe. The shape of the leadframe has two purposes; it signifies which lead is the cathode and anode, and also helps the leadframe stay anchored in place after it is dipped in epoxy resin. Electrical current can now travel in a circuit through the anode, up the post, across the wire, through the semiconductor, down the anvil, and out through the cathode.
The semiconductor inside the LED is made up of two types of materials, N-type material, and P-type material. The N-type material has extra electrons while the P-type material has electron holes for electrons to go. There is a gap in between the materials called a p-n junction. When a current is applied to the circuit, electrons and holes flow into the junction. When an electron and a hole meet, the electron releases energy in the form of a photon, or light. A reflective cavity is placed on top of the semiconductor so that most of the photons are projected out and away from the semiconductor. The lens, or case of the LED is also designed so that most of the light is sent out toward the round end of the case.
A light bulb powered by Light Emitting Diodes can offer the same level of brightness as a traditional light bulb, but require significantly less power to operate. Because LEDs use semiconductors, which are in between an electrical conductor and an insulator, LEDs last longer than incandescent bulbs and can give off the same amount of light without producing a lot of heat.