How Does an LED Projector Work?

Light-emitting diode projectors represent a significant advance over traditional projectors. Instead of using a bulb filled with gas at high pressure, they use an array of LEDs to generate the light that shines through, or off of, the image element to project an image. LED projectors run cooler, consume less energy, have more accurate color and can last longer without a replacement bulb than a traditional projector, making them ideal in many ways for use in an business environment.

The LEDs in an LED projector use a process called "electroluminescence" to produce light. In a bulb, electricity passes through a wire, making it heat up to the point that it glows. LEDs, on the other hand, use semiconducting materials which allow certain types of energy to pass through them. When an electrical signal passes through the material in an LED, it kicks off electrons that are too big to pass through. To shrink themselves, they give off a photon, which is a particle of light, which then allows them to fit through to the other side. Since this process generates very little heat, it consumes much less power than a traditional bulb. It also puts much less stress on the LED, which is why it lasts so much longer than a regular lamp.

Instead of a bulb, projectors have arrays of red, green and blue LEDs. When mixed, they generate a very accurate color of white light. This light then gets reflected off of an array of tiny mirrors (in a projector with a Digital Light Processing chip) or gets passed through a sandwich of liquid crystal display layers (in an LCD projector). In other words, LED projectors are almost exactly the same as any other projector, except for the bulb.

LEDs run much cooler than traditional bulbs, so LED projectors can be smaller and quieter, since they do not need as much airflow or insulation to protect their users from a hot bulb. The combination of red, green and blue LEDs makes a white light that is a better representation of true white than most bulbs can generate. This gives LED projectors the ability to reproduce more colors than other projectors. Finally, because LEDs last so much longer than bulbs, LED projectors should never need a replacement. A 20,000 hour bulb will run for eight hours a day, seven days a week, for six years and ten months. It will last for over 27 years if used for four hours a day, five days a week.

LED projectors have one key drawback. As of the time of publication, they have the same problem as LED light bulbs – LEDs are expensive. While LED projectors are available at roughly similar costs to projectors with traditional lamps, they usually have much lower light output ratings. For example, one manufacturer's lineup includes a 3,000 lumen model, a 2,600 lumen model and a 500 lumen LED projector, all with similar suggested retail prices and specifications.