Projectors: LCD Verses DLP (The downfall of DLP technology)
July 19th, 2010
The most common question heard when purchasing a new projector for the home, office, or classroom is: will I buy an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and different models available, it can be difficult for consumers to pick between those technologies. Ultimately LCD projectors have far superior image quality and colour accuracy. The article below will tell you why DLP projectors struggle with bringing up the same standard of image quality.
Imagine a set of blinds in your household over your bedroom window. By a twist of a rod you can turn the shutters open or closed, depending on if you want to let light in or not. This is exactly how an LCD projector functions. Each pixel operates like a unique shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is formed 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 the point at which the projector is turned on to when the image reaches your screen is vitally 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 direct the coloured light to 3 stand alone LCD panels. The 3 LCD panels create the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to form the projector image. A significant point to realise about LCD projectors is that all three colours are sent onto your screen simultaneously. The way a DLP projector runs is totally different and even the final product of how an image appears 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 way of projecting an image casts a sequence of red, blue and green light. The millions of micro mirrors mentioned 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 eyes will then combine each coloured element of the image into a full image. With LCD projectors, all colours are available all the time to offer top brightness and great colour accuracy. In DLP, just one colour is available at once, and so causing lower colour brightness and accuracy. Some designers have placed a white segment for the colour wheel to improve all over brightness, but this further lessens colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and ergo must be better. For those who are 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 machine is able to produce. DLP projectors do offer high contrast specifications in comparison to the majority of LCD projectors. At a 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 in use. Do not be fooled by contrast specifications on websites and in brochures.
When the content you are trying to view has moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images keep changing between the time red, blue and green colours are pulled up. LCD projectors do not have this problem because the colours are processed at the same time. DLP developers have developed 3DLP solutions using 3 chips to solve the colour break up problem, but the price of these projectors make them hardly practical for the majority of businesses and consumers.
Another variance between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and recall how different colours of light refract various amounts when directed through the same lens. The problem with DLP projectors is that they take the one same panel with the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Most of the time with a DLP projector, a superfluous yellow colour will come up above and some extra blue will come through below an image containing something as simple as a single black line. During manufacturing LCD projectors can be adapted to reduce these effects on the projected image, because each colour is projected on its own LCD panels.
The one true plus (excluding price) with deciding on a DLP projector is its smaller overall size and weight. However, this is only relevant with regard to portability and cannot be traded off against the image plusses of LCD projectors. If overall picture quality is vital to you, then the decision is easy. Take an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image errors. If you want to ask more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any further questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s premier online retailer for projectors. Based in Brisbane, Projector Central has served Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
Sphere: Related ContentCategories: General Travel Information | Tags: data projectors brisbane, data projectors gold coast
