Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question customers ask when purchasing a new projector for the home, office, or classroom is: should I get an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most common projector imaging technologies. With so many brands and different models available, it can be difficult for consumers to pick between these technologies. The fact is that LCD projectors offer superior image quality and colour accuracy. The following article tells you why DLP projectors struggle with creating an equal grade of image quality.
Imagine a set of blinds in your house over your bedroom window. By pulling a rod you can turn the shutters open or closed, depending on if you want to let light in or not. That is exactly how an LCD projector functions. Each pixel functions like a single shutter on a set of blinds to either send 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 functions to either reflect light or block it.
How the light source is processed from the point when the projector switches on to when the content reaches your screen is vitally significant in regard to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by splitting 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 cast the elements of the image by shining each pixel on and off. The pixels are then meshed in a glass prism to send the projector image. A significant point to remember about LCD projectors is that all three colours are delivered onto your projector screen all at once. The way a DLP projector functions is widely different and even the way an image shows up is not the same. With DLP, white light from the lamp is processed 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 casts a sequence of red, blue and green light. The millions of micro mirrors 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 single complete image. With LCD projectors, all colours are available all the time to offer the top level of brightness and great colour accuracy. In DLP, just one colour is available at once, causing lower colour brightness and accuracy. Some manufacturers have included a white segment for the colour wheel to improve general brightness, but this further detracts from colour accuracy.
I see in forums all the time that DLP gives a higher contrast ratio and ergo must be better quality. For those 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 capable of. DLP projectors do offer high contrast specifications as compared to a majority of LCD projectors. At one glance, this can seem to be a benefit, however, in reality, the true black level is determined by the ambient light in the room where the projector is used. Do not be fooled by contrast specifications on websites and in brochures.
When the content you wish to view includes moving images, DLP projection technology also has image imperfections, 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 keep changing between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because all colours are projected at the same time. DLP developers have formed 3DLP solutions using 3 chips to answer the colour break up artifacts, but the price of these projectors make them hardly practical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they balance for the refractive qualities of light. Remember back to high school science, and they taught you how various colours of light refract different amounts when directed through the same lens. The downfall 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 obviously not the same and refract light in a different way. Most of the time with a DLP projector, some yellow colour will appear above and a superfluous blue will come up below something as simple as a lone black line. In manufacturing LCD projectors can be set to take away these effects on the projected image, because each colour is processed on its own LCD panels.
The only true benefit (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant for portability and needs to be traded off against the image advantages of LCD projectors. If overall picture quality is crucial to you, then the solution is easy. Choose an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you wish to know more about LCD technology in more detail, see this fabulous 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 at Projector Central, Australia’s top online retailer 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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