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The typical question heard when buying a new projector for the home, office, or classroom is: should I purchase an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most common projector imaging technologies. With so many company brands and different types available, it can be difficult for customers to decide between the two technologies. It comes down to the fact that LCD projectors offer superior image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with creating a similar level of image quality.

It’s like a set of blinds in your house covering your bedroom window. With the twist of a rod you can make the shutters open or closed, depending on whether you want to let light in or not. And that is exactly how an LCD projector functions. Each pixel functions like a unique 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 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 at which the projector switches on to when the content reaches your screen is extremely important to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. Something important to remember about LCD projectors is that all three colours are projected onto your projected surface all at the same time. The way a DLP projector functions is very different and even the way an image comes out is not the same. With DLP, white light from the lamp is sent through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to making an image casts a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to construct 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 pull together each coloured element of the image into a single whole image. Using LCD projectors, all colours are available all the time to create 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 DLP developers have placed a white segment for the colour wheel to improve brightness generally, but this further degrades colour accuracy.

I read in forums all the time that DLP gives a higher contrast ratio and as such 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 capable of producing. DLP projectors do provide high contrast specifications in comparison to most LCD projectors. At a glance, this can seem to be a plus, 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 tricked by contrast specifications on websites and in brochures.

When the content you wish to project needs 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 incontrovertible in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this characteristic because every colour is processed simultaneously. DLP builders have come up with 3DLP solutions using 3 chips to solve the colour break up error, but the expense 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 different amounts when shone through the same lens. The disadvantage with DLP projectors is that they utilise the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously not the same and refract light at different levels. Most of the time with a DLP projector, some extra yellow colour will be projected above and a spill of blue will appear below an image as simple as a lone black line. In building LCD projectors can be adjusted to reduce these effects on the projected image, because each colour is processed on isolated LCD panels.

The isolated true buy point (excluding price) with taking a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to portability and must be traded off against the image advantages of LCD projectors. If the outcome of the picture quality is crucial to you, then the choice is simple. Go for an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image errors. If you want to learn more about LCD technology in more detail, have a look at this fantastic 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 with Projector Central, Australia’s premier online retailer 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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