The most typical question asked when acquiring a new projector for the home, office, or classroom is: would I get 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 different models available, it can be difficult for consumers to make a decision between both technologies. Ultimately LCD projectors offer superior image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with projecting an equal level of image quality.

It’s like a set of blinds in your room on your bedroom window. By twisting a rod you can make the shutters open or closed, according to if you want to let light in or not. And that is exactly how an LCD projector works. Each pixel operates like its own shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from the time the projector turns on to when the picture reaches your screen is ultimately important to image quality, brightness and colour accuracy. LCD projectors direct 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 create the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. A significant point to remember about LCD projectors is that all three colours are projected onto your projected surface simultaneously. The way a DLP projector operates is widely different and even the final product of how an image shows up 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 approach to projecting an image creates a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to produce 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 put together each coloured element of the image into the single whole image. From LCD projectors, all colours are available all the time to create high brightness and great colour accuracy. In DLP, just one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP designers have added a white segment for the colour wheel to improve brightness overall, but this goes and detracts from colour accuracy.

I hear in forums all the time that DLP provides a higher contrast ratio and ergo must be superior quality. For those who don’t 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 system is capable of. DLP projectors do provide high contrast specifications as compared to most LCD projectors. At a glance, this must be an advantage, however, in the real world, the true black level is determined by the ambient light in the room while the projector is being utilised. Do not be fooled by contrast specifications on websites and in brochures.

When the content you are trying to project has moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector shows with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change position between the time red, blue and green colours are pulled up. LCD projectors do not have this problem because all the colours are processed with the others. DLP builders have created 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the price tag of these projectors make them hardly practical for many businesses and consumers.

Another differentiation 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 when they taught you how different colours of light refract different amounts when passing through the same lens. The problem with DLP projectors is that they take 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 in different ways. Usually with a DLP projector, some yellow colour will come up above and some extra blue will come through below an image as simple as a lone black line. During manufacturing LCD projectors can be set to minimize these effects on the projected image, because each colour is directed on separate LCD panels.

The one real buy point (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant to mobility and cannot be traded off against the image plusses of LCD projectors. If the result of the picture quality is vital to you, then the choice is easy. Choose an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image errors. If you need to know more about LCD technology in more detail, have a look at this fantastic resource website: Explore 3LCD. If you have any other questions, visit Projector Central and send me an email.

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