Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question asked when buying a new projector for the home, office, or classroom is: will I get an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and different types available, it can be overwhelming for customers to pick between those technologies. The fact is that LCD projectors provide superior image quality and colour accuracy. The article below will explain why DLP projectors struggle with reproducing an equal grade of image quality.
Imagine a set of blinds in your room for your bedroom window. By pulling a rod you can make the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector behaves. Each pixel functions like its own shutter on a set of blinds to either send light through or to block it. DLP on the other hand is created 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 switches on to when the picture reaches your screen is absolutely important with regard 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 transfer the coloured light to 3 separate LCD panels. The 3 LCD panels create the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. A significant point to remember about LCD projectors is that all three colours are sent onto your projected surface at once. The way a DLP projector runs is totally different and even the produced image comes out is not the same. With DLP, white light from the lamp is sent through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of 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 create the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into the single complete image. With LCD projectors, all colours are available all the time to offer the highest brightness and great colour accuracy. In DLP, just one colour is available at once, causing lower colour brightness and accuracy. Some DLP designers have placed a white segment in the colour wheel to improve brightness generally, but this also lessens colour accuracy.
I find in forums all the time that DLP gives a higher contrast ratio and therefore must be superior quality. For those uncertain, 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 technology is capable of producing. DLP projectors do possess high contrast specifications when compared to a majority of LCD projectors. At one glance, this seems to be a plus, however, in real life, the true black level is determined by the ambient light in the room where the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to bring to life includes moving images, DLP projection technology also has image errors, or ‘artifacts’. The most often seen 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 projected. LCD projectors do not have this downside because all the colours are processed simultaneously. DLP builders have developed 3DLP solutions using 3 chips to resolve the colour break up error, but the price of these projectors make them not practical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Take yourself back to high school science, and they taught you how the different colours of light refract differing amounts when directed through the same lens. The problem 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. Often with a DLP projector, an extra yellow colour will come up above and some blue will come up below an image containing something as simple as a single black line. In building LCD projectors can be adjusted to remove these effects on the projected image, because each colour is processed on separate LCD panels.
The one veritable benefit (excluding price) with going with a DLP projector is its smaller size and weight. However, this is only relevant in regard to portability and needs to be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is important to you, then the solution is easy. Go for an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image blips. If you need to find out more about LCD technology in more detail, have a gander at this tremendous resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s top online store for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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