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The common question customers ask when buying a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and models available, it can be overwhelming for clients to make a decision between these technologies. Ultimately LCD projectors offer far better image quality and colour accuracy. The following article tells you why DLP projectors struggle with reproducing the same rate of image quality.

Visualise a set of blinds in your house on your bedroom window. By pulling a rod you can turn the shutters open or closed, according to if you want to let light in or not. And this is exactly how an LCD projector functions. Each pixel works like a single shutter on a set of blinds to either send light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the professionals 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 picture reaches your screen is vitally significant to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to send the projector image. An important point to realise about LCD projectors is that all three colours are directed onto your screen all at once. The way a DLP projector works is totally different and even the produced image appears is not the same. With DLP, white light from the lamp is projected through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of creating an image casts a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to create the image elements. The elements of the image are sent 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 a single full image. In LCD projectors, all colours are available all the time to form the top level of brightness and superb colour accuracy. In DLP, just one colour is available at a time, and so causing lower colour brightness and accuracy. Some designers have put a white segment into the colour wheel to improve brightness overall, but this further damages colour accuracy.

I find in forums all the time that DLP has a higher contrast ratio and as such 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 machine is capable of producing. DLP projectors do provide high contrast specifications in comparison to the majority of LCD projectors. At a glance, this appears to be an advantage, however, in real life, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.

When the content you plan to see has moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector shows with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change between the time red, blue and green colours are projected. LCD projectors do not have this characteristic because the colours are delivered at once. DLP developers have come up with 3DLP solutions using 3 chips to fix the colour break up error, but the price tag of these projectors make them almost impossible for most businesses and consumers.

Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and recall how the different colours of light refract different amounts when projected through the same lens. The downside 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 different ways. Most of the time with a DLP projector, some yellow colour will come up above and a superfluous blue will be projected below something as simple as a single black line. In building LCD projectors can be fixed to take away these effects on the projected image, as each colour is processed on separate LCD panels.

The sole real buy point (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant for transporting the device and must be traded off against the image advantages of LCD projectors. If overall picture quality is crucial to you, then the answer is simple. Choose an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image blips. If you wish to learn more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any other questions, jump onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager at Projector Central, Australia’s number one online retailer 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.