Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question that is asked when looking for a new projector for the home, office, or classroom is: would I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and different types available, it can be overwhelming for the buyer to make a decision between both technologies. It comes down to the fact that LCD projectors offer better image quality and colour accuracy. The next paragraph will tell you why DLP projectors struggle with reproducing a comparable level of image quality.
Think of a set of blinds in your house on your bedroom window. By pulling a rod you can make the shutters open or closed, depending on whether you want to let light in or not. And that is exactly how an LCD projector behaves. Each pixel functions like an individual shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as the professionals like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the point at which the projector is switched on to when the image reaches your screen is ultimately significant with regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels make the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. Something important to remember about LCD projectors is that all three colours are directed onto your screen all at the same time. The way a DLP projector functions is vastly different and even how an image shows up is not the same. With DLP, white light from the lamp is sent through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of forming an image requires a sequence of red, blue and green light. The millions of micro mirrors mentioned 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 combine each coloured element of the image into the total image. With LCD projectors, all colours are available all the time to deliver top brightness and superb colour accuracy. In DLP, just one colour is available at once, causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment in the colour wheel to improve overall brightness, but this further damages colour accuracy.
I see in forums all the time that DLP provides a higher contrast ratio and as such must be better quality. 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 technology is able to produce. DLP projectors do have high contrast specifications when compared to a majority of LCD projectors. Initially, this seems to be an advantage, however, in the real world, the true black level is determined by the ambient light in the room where the projector is utilised. Do not be duped by contrast specifications on websites and in brochures.
When the content you are trying to project needs moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector displays with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this downside because all colours are delivered at the same time. DLP developers have formed 3DLP solutions using 3 chips to fix the colour break up artifacts, but the cost of these projectors make them hardly practical for the majority of businesses and consumers.
Another point of difference between LCD and DLP is how they make up for the refractive qualities of light. Take yourself back to high school science, and remember how the various colours of light refract different amounts when shone through the same lens. The disadvantage 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 not the same and refract light at different levels. Often with a DLP projector, a spill of yellow colour will appear above and a superfluous blue will show below something as simple as a single black line. During 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 isolated veritable plus (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant to portability and cannot be traded off against the image plusses of LCD projectors. If overall picture quality is crucial to you, then the solution is easy. Go for an LCD projector! LCD projectors will consistently produce bright, colourful images with fewer image mistakes. If you want to find out more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any persisting questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s number one online store for projectors. Brisbane-based, 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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