Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when looking for a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many company brands and types available, it can be challenging for the buyer to make a choice between both technologies. It comes down to the fact that LCD projectors give superior image quality and colour accuracy. The article below will explain why DLP projectors struggle with projecting an equal level of image quality.
Imagine a set of blinds in your home over your bedroom window. By twisting a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And that is exactly how an LCD projector functions. 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 experts like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the time the projector is switched on to when the picture reaches your screen is absolutely important for 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 project the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then projected in a glass prism to send the projector image. Something important to realise about LCD projectors is that all three colours are sent onto your wall at once. The way a DLP projector functions is totally different and even the final product of how an image shows up is not the same. With DLP, white light from the lamp is processed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image forms a sequence of red, blue and green light. The millions of micro mirrors as 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 pull together each coloured element of the image into a single total image. In LCD projectors, all colours are available all the time to deliver top brightness and fantastic colour accuracy. In DLP, just one colour is available at once, causing lower colour brightness and accuracy. Some DLP designers have added a white segment for the colour wheel to improve all over brightness, but this then damages colour accuracy.
I hear in forums all the time that DLP gives 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 capable of. DLP projectors do provide high contrast specifications when compared to a majority of LCD projectors. At one glance, this appears to be a plus, however, in the real world, the true black level is determined by the ambient light in the room where the projector is being used. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to see has moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most typical 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 position between the time red, blue and green colours are pulled up. LCD projectors do not have this characteristic because every colour is sent at the same time. DLP builders have created 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the price tag of these projectors make them hardly practical for the large part of businesses and consumers.
Another 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 different colours of light refract various amounts when shone through the same lens. The downside with DLP projectors is that they utilise the one same panel and the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light differently. Usually with a DLP projector, a superfluous yellow colour will appear above and some blue will be projected below something as simple as a single black line. During manufacturing LCD projectors can be adjusted to minimize these effects on the projected image, because each colour is processed on isolated LCD panels.
The only real buy point (excluding price) with picking a DLP projector is its overall smaller size and weight. However, this is only relevant for transport and has to be traded off against the image advantages of LCD projectors. If resulting picture quality is vital to you, then the answer is no-brainer. Choose an LCD projector! LCD projectors will always show bright, colourful images with fewer image blips. If you desire to find out more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any more questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s top online shop for projectors. Brisbane-based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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