The most common question asked when looking for a new projector for the home, office, or classroom is: should I buy an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most popular projector imaging technologies. With so many company brands and types available, it can be difficult for the buyer to choose between both technologies. It comes down to the fact that LCD projectors offer superior image quality and colour accuracy. The following article explains why DLP projectors struggle with bringing up a comparable grade of image quality.
Think of a set of blinds in your house for your bedroom window. With the twist of a rod you can turn the shutters open or closed, according to if you want to let light in or not. That is exactly how an LCD projector operates. Each pixel operates like a single shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point at which the projector is switched on to when the picture reaches your screen is extremely significant for image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 individual LCD panels. The 3 LCD panels make the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to create the projector image. Something important to realise about LCD projectors is that all three colours are sent onto your projector screen at once. The way a DLP projector runs is very different and even how an image appears is not the same. With DLP, white light from the lamp is sent through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of projecting an image forms a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to produce the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into a single whole image. In LCD projectors, all colours are available all the time to form the top level of brightness and fantastic colour accuracy. In DLP, just one colour is available at any given time, and so causing lower colour brightness and accuracy. Some manufacturers have added a white segment for the colour wheel to improve all over brightness, but this then degrades colour accuracy.
I find in forums all the time that DLP provides a higher contrast ratio and thus must be better quality. For those who do not know, 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 able to produce. DLP projectors do possess high contrast specifications compared to the majority of LCD projectors. At first glance, this appears to be a benefit, however, in the real world, the true black level is determined by the ambient light in the room in which the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you want to project includes moving images, DLP projection technology also creates image errors, or ‘artifacts’. The most commonplace artifact that a DLP projector forms 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 downside because all the colours are processed with the others. DLP designers have created 3DLP solutions using 3 chips to answer the colour break up artifacts, but the price of these projectors make them not practical for the majority of businesses and consumers.
Another differentiation between LCD and DLP is how they balance for the refractive qualities of light. Remember back to high school science, and remember when they taught you how different colours of light refract varied 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 different and refract light in a different way. Usually with a DLP projector, some extra yellow colour will come up above and some extra blue will show below an image containing something as simple as a single black line. During manufacturing LCD projectors can be adapted to remove these effects on the projected image, as each colour is refracted on isolated LCD panels.
The one true advantage (excluding price) with deciding on a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to transport and must be traded off against the image plusses of LCD projectors. If resulting picture quality is important to you, then the choice is simple. Go with an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you want to know more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any persisting questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s top online retailer for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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