Projectors: LCD Verses DLP (The downfall of DLP technology)
The common 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 popular projector imaging technologies. With so many different brands and models available, it can be challenging for clients to make a choice between the two technologies. The simple fact of the matter is that LCD projectors offer superior image quality and colour accuracy. The article below will tell you why DLP projectors struggle with projecting a similar standard of image quality.
It’s like 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, according to if you want to let light in or not. And that is exactly how an LCD projector works. 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 created of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from when the projector is turned on to when the picture reaches your screen is vitally significant in regard 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 project the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by switching each pixel on and off. The pixels are then meshed in a glass prism to deliver the projector image. A significant point to remember about LCD projectors is that all three colours are directed onto your screen all at once. The way a DLP projector works is vastly different and even the produced image looks 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 creating an image requires 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 cast in sequence on the screen, one colour at a time. The viewer’s vision will then draw each coloured element of the image into a whole image. In LCD projectors, all colours are available all the time to offer 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 designers have added a white segment into the colour wheel to improve brightness overall, but this then lessens colour accuracy.
I hear in forums all the time that DLP provides a higher contrast ratio and therefore must be better. For those who do not 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 technology is capable of. DLP projectors do offer high contrast specifications as compared to many LCD projectors. At first glance, this appears to be an advantage, however, in truth, the true black level is determined by the ambient light in the room where the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to view has moving images, DLP projection technology also has image marks, or ‘artifacts’. The most often seen artifact that a DLP projector shows with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change position between the time red, blue and green colours are shone. LCD projectors do not have this downside because the colours are projected with the others. DLP designers have formed 3DLP solutions using 3 chips to answer the colour break up issue, but the expense of these projectors make them impractical 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 recall when they taught you how the various colours of light refract varied amounts when projected through the same lens. The problem with DLP projectors is that they use the one same panel for the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Often with a DLP projector, some extra yellow colour will come through above and a superfluous blue will come up below something as simple as a lone black line. In manufacturing LCD projectors can be adapted to minimize these effects on the projected image, as each colour is projected on separate LCD panels.
The one true plus (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to mobility and needs to be traded off against the image superiority of LCD projectors. If the result of the picture quality is important to you, then the solution is a no-brainer. Choose an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image mistakes. If you want to ask more about LCD technology in more detail, have a gander at this tremendous resource website: Explore 3LCD. If you have any additional questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s premier online retailer for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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