Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question heard when looking for a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most popular projector imaging technologies. With so many business brands and models available, it can be overwhelming for consumers to choose between the two technologies. The simple fact of the matter is that LCD projectors offer far superior image quality and colour accuracy. The next paragraph tells you why DLP projectors struggle with creating a comparable grade of image quality.
Think of a set of blinds in your room covering your bedroom window. With the twist of a rod you can have the shutters open or closed, according to if you want to let light in or not. Such is exactly how an LCD projector functions. 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 created 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 image reaches your screen is vitally important 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 send the coloured light to 3 separate LCD panels. The 3 LCD panels create the elements of the image by turning each pixel on and off. The pixels are then combined in a glass prism to create the projector image. A significant point to understad about LCD projectors is that all three colours are directed onto your projector screen all at once. The way a DLP projector runs is widely different and even how an 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 forming 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 produce the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s vision will then pull together each coloured element of the image into a total image. With LCD projectors, all colours are available all the time to deliver the best brightness and great colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP manufacturers have put a white segment into the colour wheel to improve all over brightness, but this goes and lessens colour accuracy.
I see in forums all the time that DLP offers a higher contrast ratio and as such must be superior quality. For those who are unsure, 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 projector is capable of producing. DLP projectors do possess high contrast specifications compared to many LCD projectors. At one glance, this must be a plus, however, in reality, the true black level is determined by the ambient light in the room when the projector is in use. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you plan to project has moving images, DLP projection technology also creates image errors, or ‘artifacts’. The most common artifact that a DLP projector shows with moving images is colour break up. Colour break up is to be expected 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 disadvantage because all the colours are sent simultaneously. DLP builders have created 3DLP solutions using 3 chips to answer the colour break up error, but the price of these projectors make them impractical for most businesses and consumers.
Another point of difference between LCD and DLP is how they make up for the refractive qualities of light. Remember back to high school science, and remember how the various colours of light refract varied amounts when projected through the same lens. The problem with DLP projectors is that they utilise the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in different ways. Usually with a DLP projector, a spill of yellow colour will show above and an extra blue will show below something as simple as a straight black line. During manufacturing LCD projectors can be fixed to reduce these effects on the projected image, because each colour is projected on isolated LCD panels.
The one true plus (excluding price) with choosing a DLP projector is its smaller size and weight. However, this is only relevant to transporting the device and needs to be traded off against the image plusses of LCD projectors. If resulting picture quality is important to you, then the answer is no-brainer. Take an LCD projector! LCD projectors will always create bright, colourful images with fewer image imperfections. If you wish to find out more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any further questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s leading online shop 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.
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