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The most common question customers ask when buying a new projector for the home, office, or classroom is: will I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two top projector imaging technologies. With so many brands and models available, it can be difficult for clients to make a decision between both technologies. The fact is that LCD projectors give far superior image quality and colour accuracy. The following article will explain why DLP projectors struggle with bringing up a similar standard of image quality.

Visualise a set of blinds in your household covering your bedroom window. By a twist of a rod you can make the shutters open or closed, depending on whether you want to let light in or not. And this is exactly how an LCD projector operates. Each pixel works like a unique 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 experts like to call them. Each pixel element functions to either reflect light or block it.

How the light source is processed from the time the projector is turned on to when the picture reaches your screen is vitally important to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by cutting it into red, blue and green components, by three mirrors which direct the coloured light to 3 separate LCD panels. The 3 LCD panels cast the elements of the image by turning each pixel on and off. The pixels are then projected in a glass prism to send the projector image. Something to know about LCD projectors is that all three colours are delivered onto your projected surface at the same time. The way a DLP projector runs is vastly different and even the final product of how an image looks is not the same. With DLP, white light from the lamp is directed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to making 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 vision will then combine each coloured element of the image into the full image. Using LCD projectors, all colours are available all the time to create the best brightness and fantastic colour accuracy. In DLP, only one colour is available at once, resulting in lower colour brightness and accuracy. Some developers have added a white segment into the colour wheel to improve overall brightness, but this also detracts from colour accuracy.

I see in forums all the time that DLP has a higher contrast ratio and ergo must be superior quality. 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 machine is capable of producing. DLP projectors do offer high contrast specifications when compared to a majority of LCD projectors. At one glance, this seems 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 in use. Do not be duped by contrast specifications on websites and in brochures.

When the content you are trying to view has moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector displays with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this downside because all colours are projected simultaneously. DLP designers have formed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the cost of these projectors make them hardly practical for the majority of businesses and consumers.

Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Jump back to high school science, and remember when they taught you how the various colours of light refract varied amounts when shone through the same lens. The downfall with DLP projectors is that they take the one same panel for the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light at different levels. Most of the time with a DLP projector, some yellow colour will show above and some extra blue will be projected below an image of something as simple as a single black line. In building LCD projectors can be adjusted to minimize these effects on the projected image, because each colour is directed on isolated LCD panels.

The sole veritable plus (excluding price) with going with a DLP projector is its smaller overall size and weight. However, this is only relevant with regard to mobility and has to be traded off against the image plusses of LCD projectors. If overall picture quality is important to you, then the solution is easy. Go for an LCD projector! LCD projectors will consistently produce bright, colourful images with fewer image errors. If you want to ask more about LCD technology in more detail, see this fabulous 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 premier online shop for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.

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