The typical question heard when purchasing a new projector for the home, office, or classroom is: would I get an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and different models available, it can be difficult for the buyer to decide between those technologies. Ultimately LCD projectors provide far superior image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with bringing up the same level of image quality.

It’s like a set of blinds in your room over your bedroom window. By a twist of a rod you can turn the shutters open or closed, depending on if you want to let light in or not. And that is exactly how an LCD projector functions. Each pixel functions 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 pros 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 is switched on to when the image reaches your screen is vitally important to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by cutting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 separate LCD panels. The 3 LCD panels create the elements of the image by processing each pixel on and off. The pixels are then projected in a glass prism to form the projector image. An important point to understad about LCD projectors is that all three colours are delivered onto your screen all at once. The way a DLP projector operates is widely different and even the produced image comes out is not the same. With DLP, white light from the lamp is directed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image creates 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 cast in sequence on the screen, one colour at a time. The viewer’s eyes will then draw each coloured element of the image into the single complete image. Using LCD projectors, all colours are available all the time to form the highest brightness and fantastic colour accuracy. In DLP, just one colour is available at once, resulting in lower colour brightness and accuracy. Some DLP designers have placed a white segment in the colour wheel to improve all over brightness, but this further degrades colour accuracy.

I read in forums all the time that DLP offers a higher contrast ratio and ergo must be better quality. For those 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. DLP projectors do possess high contrast specifications when compared to many LCD projectors. Initially, this must be a benefit, however, in real life, the true black level is determined by the ambient light in the room where the projector is used. Do not be fooled by contrast specifications on websites and in brochures.

When the content you wish to view has moving images, DLP projection technology also has image errors, or ‘artifacts’. The most often seen artifact that a DLP projector displays 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 displayed. LCD projectors do not have this downside because every colour is processed with the others. DLP builders have developed 3DLP solutions using 3 chips to answer the colour break up artifacts, but the expense of these projectors make them hardly practical for many businesses and consumers.

Another variance between LCD and DLP is how they match the balance for the refractive qualities of light. Take yourself back to high school science, and remember how different colours of light refract differing amounts when passing through the same lens. The downside with DLP projectors is that they take the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Generally with a DLP projector, an extra yellow colour will come through above and a superfluous blue will appear below an image containing something as simple as a single black line. During manufacturing LCD projectors can be fixed to remove these effects on the projected image, as each colour is refracted on isolated LCD panels.

The only actual advantage (excluding price) with going with a DLP projector is its smaller total size and weight. However, this is only relevant in regard to transport and cannot be traded off against the image advantages of LCD projectors. If resulting picture quality is important to you, then the choice is easy. Take an LCD projector! LCD projectors will definitely create bright, colourful images with fewer image imperfections. If you need to ask more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any persisting questions, visit Projector Central and send me an email.

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