Understanding the Differences between LED, LCD and DLP Projectors

Ideal for delivering lectures and presentations to large groups, as well as watching movies and other videos, projectors can be found in a variety of environments, including classrooms, conference rooms, and even home theaters. Projectors range in size and capabilities, from handheld devices that need a dark room to deliver a viewable image to high-powered devices that are easily read, even in brightly lit offices. Projectors can be purchased from electronics retailers or specialty stores dealing in camera and projection equipment. For consumers who prefer to shop online, sites like eBay are excellent options. This buying guide will discuss the differences between three kinds of projectors: LED, LCD, and DLP projectors. It will also explain how the technology works, and weigh the advantages of each for consumers.

DLP, LCD, and LED Technology
The technology used in projectors can generally be broken down into two types: transmissive or reflective. Because LCD projectors pass light through the LCD panels rather than bouncing it away, they are considered a transmissive medium. A DLP projector uses mirrors to direct the light in an image, so it is considered to be “reflective.” The third type of projector discussed, an LED projector, is named for the light source, not the type of projection technology.
How DLP Projectors Work

First appearing on the market in the 1980s, DLP projectors rely primarily on a DLP chip (called a digital micromirror device, or DMD), comprised of up to two million tiny mirrors, no wider than one-fifth the width of a human hair. Each mirror in this chip is capable of independent adjustment, moving toward or away from the light source to create a dark or light pixel. At this point, however, the image is in grayscale. Color is fed to the DMD by a beam of light that passes through a spinning color wheel before it reaches the chip. Each segment of the color wheel delivers one color. Basic color wheels support red, blue, and green, whereas more advanced color wheels support cyan, magenta, and yellow. While these chips can create up to 16.7 million colors, a DLP projector with a three-chip architecture can deliver up to 35 trillion colors. After color reaches the DMD, the image is fed through the lens and onto the projection screen.

Advantages and Disadvantages to DLP Projectors
DLP projectors require less maintenance than LCD projectors because they have a filter-free and sealed chip design, which means dust can’t settle on the chip and cause an image spot. They are effectively immune to color decay. Furthermore, they are not subject to the misalignments that can occur in LCD projectors with a three-panel design, which require each panel to be in perfect position to combine the image at the proper angle. However, DLP projectors with slower color wheels may give off a rainbow effect; flashes of color that appear on the screen, like rainbows. Furthermore, while the chip is sealed, other components are not, so dust can settle on the color wheel and affect image quality. Another disadvantage may be the poor viewing range. Most DLP projectors are not readily compatible with zoom lenses or lens shift functions, which means they are best suited to smaller environments.