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The most common question heard when purchasing a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many company brands and models available, it can be difficult for the buyer to make a decision between both technologies. The simple fact of the matter is that LCD projectors give far superior image quality and colour accuracy. The next part of this article explains why DLP projectors struggle with reproducing an equal rate of image quality.

Visualise a set of blinds in your room 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 behaves. Each pixel works like its own shutter on a set of blinds to either send light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element works to either reflect light or block it.

How the light source is processed from the point when the projector is turned on to when the picture reaches your screen is absolutely important in regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by cutting it into red, blue and green components, by three mirrors which direct the coloured light to 3 stand alone LCD panels. The 3 LCD panels create the elements of the image by processing each pixel on and off. The pixels are then projected in a glass prism to send the projector image. A significant point to realise about LCD projectors is that all three colours are delivered onto your wall all at once. The way a DLP projector operates is very different and even the produced image shows up is not the same. With DLP, white light from the lamp is projected through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of projecting an image requires a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to construct 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 combine each coloured element of the image into the complete image. From LCD projectors, all colours are available all the time to offer the best brightness and fantastic colour accuracy. In DLP, just one colour is available at any given time, and so causing lower colour brightness and accuracy. Some DLP manufacturers have put a white segment for the colour wheel to improve all over brightness, but this further lessens colour accuracy.

I find in forums all the time that DLP gives a higher contrast ratio and ergo must be superior. For those unsure, 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 as compared to many LCD projectors. At first glance, this seems to be a benefit, however, in real life, the true black level is determined by the ambient light in the room while the projector is being used. Do not be hoodwinked by contrast specifications on websites and in brochures.

When the content you want to see includes moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most common artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this problem because the colours are sent simultaneously. DLP manufacturers have come up with 3DLP solutions using 3 chips to resolve the colour break up problem, but the price of these projectors make them impractical for most businesses and consumers.

Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and remember how the various colours of light refract different amounts when projected through the same lens. The downside with DLP projectors is that they use the one same panel and the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light at different levels. Generally with a DLP projector, some extra yellow colour will come through above and some extra blue will appear below something as simple as a single black line. In manufacturing LCD projectors can be adjusted to remove these effects on the projected image, because each colour is directed on separate LCD panels.

The one true benefit (excluding price) with picking a DLP projector is its smaller total size and weight. However, this is only relevant in regard to transport and must be traded off against the image benefits of LCD projectors. If the result of the picture quality is important to you, then the decision is no-brainer. Choose an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image blips. If you wish to know more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any additional questions, get onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager of Projector Central, Australia’s premier online shop for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.

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