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The most typical question heard when purchasing a new projector for the home, office, or classroom is: do 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 commonplace projector imaging technologies. With so many different brands and types available, it can be difficult for consumers to decide between those technologies. Ultimately LCD projectors have far better image quality and colour accuracy. The following article will tell you why DLP projectors struggle with reproducing a comparable grade of image quality.

Imagine a set of blinds in your home 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. This is exactly how an LCD projector functions. Each pixel works like an individual shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element functions to either reflect light or block it.

How the light source is processed from the point when the projector turns on to when the content reaches your screen is extremely important for image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 stand alone LCD panels. The 3 LCD panels make the elements of the image by switching each pixel on and off. The pixels are then simultaneously processed in a glass prism to form the projector image. Something important to realise about LCD projectors is that all three colours are sent onto your projector screen simultaneously. The way a DLP projector functions is vastly different and even the way an image shows up 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 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 produce the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s eye will then put together each coloured element of the image into the whole image. Using LCD projectors, all colours are available all the time to create top brightness and superb colour accuracy. In DLP, just one colour is available at a time, and so causing lower colour brightness and accuracy. Some DLP developers have put a white segment in the colour wheel to improve brightness overall, but this also lessens colour accuracy.

I read in forums all the time that DLP offers a higher contrast ratio and as such must be superior. 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 projector is capable of producing. DLP projectors do have high contrast specifications compared to the majority of LCD projectors. At one glance, this can seem to be a benefit, however, in reality, the true black level is determined by the ambient light in the room in which the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.

When the content you are trying to see includes moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is unavoidable 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 the colours are delivered simultaneously. DLP designers have developed 3DLP solutions using 3 chips to fix the colour break up artifacts, but the price of these projectors make them not practical for most businesses and consumers.

Another variance between LCD and DLP is how they make up for the refractive qualities of light. Jump 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 disadvantage 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 not the same and refract light in a different way. Generally with a DLP projector, an extra yellow colour will appear above and a superfluous blue will come up below an image containing something as simple as a straight black line. While being built LCD projectors can be adjusted to remove these effects on the projected image, because each colour is refracted on a separate LCD panels.

The only true advantage (excluding price) with buying a DLP projector is its smaller size and weight. However, this is only relevant to transport and must be traded off against the image benefits of LCD projectors. If resulting picture quality is important to you, then the answer is simple. Take an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image errors. If you want to know more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any more questions, get 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 serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.