In this article, we are going to pull apart an LED light bulb so you all can take a look inside and see what they’re made of.
All LED light bulbs and fixtures share the same principles in common. The way they turn electricity into light needs just a few main steps.
Let’s start with the base.
The base takes the raw AC electricity coming from your light fixture. This screw-in base is most common among light bulbs in the US.
The raw electricity is then passed into an LED driver that first converts it from AC to DC. It’s made up of electrical circuitry and it’s the driver’s job to change the voltage and current to the exact type needed by the LED chips.
The driver is finely tuned and as you can see in Figure 1 the red and black, positive and negative, wires that run from the driver through the middle of the heat sink into the LEDs.
Figure 2 shows the PCB board – a printed circuit board that wires up the LED chips and mounts them in place. You can barely make out the connection between each LED chip under the surface of the PCB board.
The LED chip is the star of the show. These little yellow mounds can come in either a square or round package, be bigger or smaller, and put out different amounts of light. They also come in different colors, usually from a warm white to a cool white. Although they look yellow, the light they put out when turned on is going to be white. Some LED bulbs of this type will use only one high powered LED chip to generate all the light it needs, and some like this one will use multiple smaller chips.
The PCB board with LED chips is made first, and then mounted to the heat sink usually with thermal glue.This one also has a couple screws holding it down. Now the thermal glue is called that because it has two jobs – to glue the board to the heat sink, and to transfer the heat generated from the chip away and into the heat sink.
The heat sink that holds this all together also has two jobs –the most important is to draw heat away from both the LED driver and LED chips. The heat sink is often made of aluminum for its good conductive qualities. The thin fins on the outside are designed to take what little circulating air is available and transfer heat from the aluminum to the air. This keeps the LED bulb as cool as possible, which makes for longer lifetimes.
Finally we have the cover. The cover for an A series LED bulb is usually just a frosted dome. It serves to keep the LED chips away from the elements. But other types of LED bulbs have their LED chips covered with lenses that are greatly effective at focusing the light produced, just like the PAR or MR16 LED.
That’s it for this one. For questions, you can ask them in the comments below, and Ill personally answer them. You can also watch a video version of this article on YouTube: http://www.youtube.com/watch?v=OYEj-hPIIv4.