Projectors: LCD Verses DLP (The downfall of DLP technology)
The common 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, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and different types available, it can be challenging for clients to make a choice between both technologies. The fact is that LCD projectors offer better image quality and colour accuracy. The following article tells you why DLP projectors struggle with reproducing an equal standard of image quality.
Imagine a set of blinds in your room covering 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. This is exactly how an LCD projector works. Each pixel operates like its own shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point at which the projector switches on to when the picture reaches your screen is ultimately significant with 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 transfer the coloured light to 3 separate LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to send the projector image. Something to understad about LCD projectors is that all three colours are delivered onto your wall at the same time. The way a DLP projector operates is vastly different and even the produced image looks is not the same. With DLP, white light from the lamp is projected through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to creating an image forms a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to construct 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 draw each coloured element of the image into the single total image. Using LCD projectors, all colours are available all the time to form the highest brightness and superb colour accuracy. In DLP, just one colour is available at any given time, causing lower colour brightness and accuracy. Some developers have added a white segment into the colour wheel to improve general brightness, but this also degrades colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and therefore must be better. For those who are unaware, 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 able to produce. DLP projectors do provide high contrast specifications as compared to most LCD projectors. At a glance, this must 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 fooled by contrast specifications on websites and in brochures.
When the content you are trying to project includes moving images, DLP projection technology also has image marks, or ‘artifacts’. The most often seen artifact that a DLP projector shows with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this downside because all the colours are sent at the same time. DLP developers have created 3DLP solutions using 3 chips to resolve the colour break up issue, but the price of these projectors make them almost impossible for many 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 the various colours of light refract different amounts when passing through the same lens. The problem with DLP projectors is that they have the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in a different way. Most of the time with a DLP projector, a spill of yellow colour will show above and a superfluous blue will come up below something as simple as a single black line. In building LCD projectors can be adapted to take away these effects on the projected image, because each colour is projected on separate LCD panels.
The sole real advantage (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant to transporting the device and must be traded off against the image plusses of LCD projectors. If the result of the picture quality is crucial to you, then the solution is easy. Go with an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image mistakes. If you wish to know more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s leading online provider for projectors. Based in Brisbane, 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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