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The typical question asked when purchasing a new projector for the home, office, or classroom is: should I take 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 different brands and types available, it can be overwhelming for clients to make a decision between the two technologies. The fact is that LCD projectors provide far better image quality and colour accuracy. The following article tells you why DLP projectors struggle with bringing up the same level of image quality.

Visualise a set of blinds in your house over your bedroom window. By pulling a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And this is exactly how an LCD projector operates. 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 made up of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from the point when the projector switches on to when the content reaches your screen is vitally important to 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 direct the coloured light to 3 different LCD panels. The 3 LCD panels form the elements of the image by turning each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. A significant point to realise about LCD projectors is that all three colours are directed onto your wall at the same time. The way a DLP projector runs is vastly different and even the final product of how an image appears 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 projecting an image forms a sequence of red, blue and green light. The millions of micro mirrors as mentioned 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 eyes will then pull together each coloured element of the image into the complete image. With LCD projectors, all colours are available all the time to offer the best brightness and great 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 in the colour wheel to improve overall brightness, but this further degrades colour accuracy.

I see in forums all the time that DLP gives a higher contrast ratio and thus must be better. For those who are unaware, 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 able to produce. DLP projectors do possess high contrast specifications compared to a majority of LCD projectors. At first glance, this must be a benefit, however, in truth, the true black level is determined by the ambient light in the room in which the projector is being utilised. Do not be duped by contrast specifications on websites and in brochures.

When the content you wish to see has moving images, DLP projection technology can also have image errors, or ‘artifacts’. The most typical artifact that a DLP projector displays with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images keep changing between the time red, blue and green colours are projected. LCD projectors do not have this problem because the colours are sent at once. DLP manufacturers have developed 3DLP solutions using 3 chips to resolve the colour break up problem, but the price of these projectors make them almost impossible for the large part of businesses and consumers.

Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and remember when they taught you how the different colours of light refract differing amounts when shone through the same lens. The downfall 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 differently. Often with a DLP projector, a superfluous yellow colour will come up above and a spill of blue will be projected below an image containing something as simple as a lone black line. During manufacturing LCD projectors can be set to reduce these effects on the projected image, as each colour is projected on isolated LCD panels.

The only true advantage (excluding price) with going with a DLP projector is its overall smaller size and weight. However, this is only relevant for transporting the device and cannot be traded off against the image advantages of LCD projectors. If resulting picture quality is important to you, then the decision is simple. Go for an LCD projector! LCD projectors will always produce bright, colourful images with fewer image errors. If you desire to find out more about LCD technology in more detail, have a gander at this spectacular resource website: Explore 3LCD. If you have any more questions, visit Projector Central and send me an email.

Jonathan King is the sales and marketing manager with Projector Central, Australia’s top online provider for projectors. Based in Brisbane, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.

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