Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question customers ask when purchasing a new projector for the home, office, or classroom is: do I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many brands and different models available, it can be difficult for customers to make a decision between both technologies. The fact is that LCD projectors provide better image quality and colour accuracy. The next part of this article will explain why DLP projectors struggle with bringing up a similar grade of image quality.
Imagine a set of blinds in your home over your bedroom window. By pulling a rod you can turn the shutters open or closed, according to whether 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 pros 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 switches on to when the image reaches your screen is absolutely significant in regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 different LCD panels. The 3 LCD panels form the elements of the image by shining each pixel on and off. The pixels are then meshed in a glass prism to send the projector image. A significant point to realise about LCD projectors is that all three colours are sent onto your wall at the same time. The way a DLP projector functions is widely different and even the produced image appears is not the same. With DLP, white light from the lamp is directed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to projecting an image creates a sequence of red, blue and green light. The millions of micro mirrors as described 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 eye will then pull together each coloured element of the image into a complete image. Using LCD projectors, all colours are available all the time to form high brightness and superb colour accuracy. In DLP, just one colour is available at once, and so resulting in lower colour brightness and accuracy. Some developers have placed a white segment into the colour wheel to improve brightness overall, but this also lessens colour accuracy.
I read in forums all the time that DLP provides a higher contrast ratio and as such must be better. 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 system is able to produce. DLP projectors do offer high contrast specifications as compared to the majority of LCD projectors. At a glance, this can seem to be a plus, however, in truth, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you are trying to view includes moving images, DLP projection technology also creates image errors, or ‘artifacts’. The most often seen artifact that a DLP projector forms with moving images is colour break up. Colour break up is to be expected 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 at once. DLP builders have formed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the expense of these projectors make them impractical for the majority of businesses and consumers.
Another difference between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and recall how various colours of light refract various amounts when directed through the same lens. The problem with DLP projectors is that they utilise the one same panel and the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light in different ways. Most of the time with a DLP projector, a spill of yellow colour will be projected above and an extra blue will come through below something as simple as a single black line. While being built LCD projectors can be set to take away these effects on the projected image, because each colour is directed on isolated LCD panels.
The sole actual benefit (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant to mobility and has to be traded off against the image advantages of LCD projectors. If the result of the picture quality is vital to you, then the answer is simple. Go with an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image blips. If you desire to learn more about LCD technology in more detail, have a gander at this fantastic 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 for Projector Central, Australia’s premier online provider for projectors. Brisbane based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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