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SHEDDING THE LIGHT ON PROJECTION |
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How does a projector work?
There are 3 types of projectors used most commonly in today’s market. They are LCD, DLP, and LCoS. Each type of projector has advantages and disadvantages. Finding the type of projector that best fits your needs is simple if you evaluate the needs you have.
LCD The technology of LCD’s has been around for years. You might remember getting a “digital” watch when you were a kid. The image was in fact an LCD. This technology uses thousands (or millions) of tiny pixels turned on or off to allow light to pass through. LCD projectors take this process one step further. Three LCD chips are placed in a block formation in front of a lens or mirror focused on a lens. Light passes through 3 special mirrors called dichotic mirrors. These mirrors separate the light in to the 3 primary colors - Red, Green and Blue. The separated light is then reflected toward the three LCD panels on the block prism where the colors are recombined to create the image you see. Because of this “pass through” technology LCD projectors give up some of their brightness from the lamp. LCD projectors are typically larger than DLP projectors of equal specifications due to this reflective design. The advantages of an LCD projector technology are vibrant color and the ability to adjust colors separately.
DLP DLP technology was developed by Texas Instruments. This technology uses tiny micro mirrors mounted on a computer chip, these mirrors tilt slightly at speeds as fast as 7,000 times per second, to allow varying shades of light to be reflected. Color is generated by a color wheel divided in to the 3 primary colors spinning at ultra high speeds. When the red, green or blue light is reflected off of the tilted mirror an image is created and focused through a lens. Advantages to DLP projector are lower cost, brighter images from the same size lamp in an LCD projector, higher contrast ratio, smaller size and lower price. The biggest disadvantage is less accurate color representation.
LCoS or D-ILA This technology invented by JVC is capable of creating extremely high quality images with a good amount contrast and less light loss than an LCD projector. Because of the high quality images that are produced from this technology, it is the preferred method for high end home theaters. LCos takes the best parts of DLP and LCD and combines them into a superior image. Light is reflected into a series of layered colored membranes and an LCD panel before being reflected back through a lens by a similar type micro mirror array as used in a DLP projector. Advantages to this type of projector are an awesome picture with no pixilation. The disadvantage is that current pricing is more than its LCD and DLP counterparts.
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