The typical question that is asked when buying a new projector for the home, office, or classroom is: should I get 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 business brands and models available, it can be confusing for customers to choose between those technologies. It comes down to the fact that LCD projectors provide superior image quality and colour accuracy. The article below explains why DLP projectors struggle with creating a comparable level of image quality.

Imagine a set of blinds in your room on your bedroom window. By a twist of a rod you can turn the shutters open or closed, according to if you want to let light in or not. And such is exactly how an LCD projector operates. Each pixel operates like an individual shutter on a set of blinds to either pass 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 functions to either reflect light or block it.

How the light source is processed from the point at which the projector turns on to when the content reaches your screen is absolutely significant for image quality, brightness and colour accuracy. LCD projectors process 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 combined in a glass prism to form the projector image. A point to realise about LCD projectors is that all three colours are sent onto your projector screen simultaneously. The way a DLP projector works is widely different and even the produced image looks is not the same. With DLP, white light from the lamp is projected through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to forming an image forms a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to form 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 combine each coloured element of the image into a complete image. In LCD projectors, all colours are available all the time to form the highest brightness and spectacular colour accuracy. In DLP, only one colour is available at a time, resulting in lower colour brightness and accuracy. Some DLP developers have placed a white segment into the colour wheel to improve brightness generally, but this goes and damages colour accuracy.

I see in forums all the time that DLP offers a higher contrast ratio and therefore must be better. 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 projector is able to produce. DLP projectors do provide high contrast specifications when compared to many LCD projectors. At a glance, this seems to be a benefit, however, in real life, the true black level is determined by the ambient light in the room where the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.

When the content you are trying to project has 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 keep changing between the time red, blue and green colours are shone. LCD projectors do not have this downside because all colours are processed simultaneously. DLP designers have come up with 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the price of these projectors make them hardly practical for most businesses and consumers.

Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and recall when they taught you how the various colours of light refract differing amounts when passing through the same lens. The downside with DLP projectors is that they have the one same panel for the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Often with a DLP projector, a spill of yellow colour will be projected above and some blue will come through below something as simple as a lone black line. In manufacturing LCD projectors can be adapted to remove these effects on the projected image, as each colour is projected on isolated LCD panels.

The only true advantage (excluding price) with taking a DLP projector is its smaller total size and weight. However, this is only relevant for transporting the device and must be traded off against the image plusses of LCD projectors. If the result of the picture quality is important to you, then the choice is easy. Go with an LCD projector! LCD projectors will definitely produce bright, colourful images with fewer image mistakes. If you need to find out more about LCD technology in more detail, check out 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 leading online provider 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.