Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question heard when buying a new projector for the home, office, or classroom is: do I purchase an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two top projector imaging technologies. With so many business brands and different models available, it can be difficult for clients to choose between both technologies. The fact is that LCD projectors give superior image quality and colour accuracy. The article below tells you why DLP projectors struggle with reproducing an equal level of image quality.
It’s like a set of blinds in your household covering your bedroom window. By pulling on a rod you can have the shutters open or closed, depending on if you want to let light in or not. And this is exactly how an LCD projector works. Each pixel works like a single 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 the experts like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from when the projector switches on to when the picture reaches your screen is vitally significant in 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 project the coloured light to 3 stand alone LCD panels. The 3 LCD panels make the elements of the image by shining each pixel on and off. The pixels are then combined in a glass prism to create the projector image. A significant point to know about LCD projectors is that all three colours are sent onto your wall at the same time. The way a DLP projector functions is vastly different and even how an image appears 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 forming 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 create 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 the total image. Using LCD projectors, all colours are available all the time to form the highest brightness and fantastic colour accuracy. In DLP, only one colour is available at a time, causing lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment for the colour wheel to improve general brightness, but this goes and lessens colour accuracy.
I read in forums all the time that DLP provides a higher contrast ratio and as such must be superior quality. 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 machine is capable of producing. DLP projectors do have high contrast specifications in comparison to many LCD projectors. At one glance, this seems to be a plus, 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 needs moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most often seen artifact that a DLP projector forms with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images keep changing between the time red, blue and green colours are displayed. LCD projectors do not have this disadvantage because all colours are delivered with the others. DLP builders have developed 3DLP solutions using 3 chips to fix the colour break up problem, but the cost of these projectors make them not practical for the majority of businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and recall how the various colours of light refract various amounts when directed through the same lens. The disadvantage 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 different and refract light at different levels. Usually with a DLP projector, a superfluous yellow colour will come up above and a superfluous blue will appear below an image as simple as a straight black line. In manufacturing LCD projectors can be set to reduce these effects on the projected image, as each colour is refracted on a separate LCD panels.
The only veritable buy point (excluding price) with picking a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to mobility and needs to be traded off against the image benefits of LCD projectors. If the result of the picture quality is vital to you, then the solution is simple. Choose an LCD projector! LCD projectors will definitely create bright, colourful images with fewer image imperfections. If you wish to learn more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any additional questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s top online provider 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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