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The common question customers ask when acquiring a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and types available, it can be difficult for consumers to make a choice between the two technologies. Ultimately LCD projectors provide better image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with projecting the same standard of image quality.

Think of a set of blinds in your household over your bedroom window. By pulling on a rod you can have the shutters open or closed, depending on whether you want to let light in or not. This is exactly how an LCD projector operates. Each pixel operates like a single shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from the point at which the projector switches on to when the picture reaches your screen is extremely important with regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by separating it into red, blue and green components, by three mirrors which project the coloured light to 3 individual LCD panels. The 3 LCD panels create the elements of the image by turning each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. Something important to understad about LCD projectors is that all three colours are delivered onto your projector screen all at the same time. The way a DLP projector works is widely different and even how an image appears is not the same. With DLP, white light from the lamp is directed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to making an image requires a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to form the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into the total image. In LCD projectors, all colours are available all the time to offer high brightness and spectacular colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP designers have added a white segment for the colour wheel to improve brightness overall, but this further detracts from colour accuracy.

I find in forums all the time that DLP gives a higher contrast ratio and thus must be better quality. For those who are uncertain, the contrast ratio is a measure of a display system defined as the ratio of the luminance of the brightest white to that of the darkest black that the technology is capable of producing. DLP projectors do offer high contrast specifications when compared to a majority of LCD projectors. Initially, this appears to be a plus, however, in the real world, the true black level is determined by the ambient light in the room where the projector is being used. Do not be fooled by contrast specifications on websites and in brochures.

When the content you are trying to view includes moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change between the time red, blue and green colours are pulled up. LCD projectors do not have this characteristic because every colour is processed at once. DLP builders have come up with 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the expense of these projectors make them almost impossible for the large part of businesses and consumers.

Another variance between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and they taught you how the different colours of light refract differing amounts when projected through the same lens. The downfall with DLP projectors is that they have the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously not the same and refract light differently. Often with a DLP projector, an extra yellow colour will come through above and a spill of blue will come through below an image as simple as a straight black line. In manufacturing LCD projectors can be adapted to minimize these effects on the projected image, as each colour is projected on a separate LCD panels.

The sole true benefit (excluding price) with buying a DLP projector is its smaller total size and weight. However, this is only relevant in regard to transport and has to be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is vital to you, then the decision is a no-brainer. Go with an LCD projector! LCD projectors will consistently make bright, colourful images with fewer image errors. If you want to ask more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.

Jonathan King is the sales and marketing manager for Projector Central, Australia’s top online retailer for projectors. Brisbane-based, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.

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