19 Jul 10 Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question that is asked when purchasing a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and types available, it can be overwhelming for customers to make a decision between both technologies. It comes down to the fact that LCD projectors have better image quality and colour accuracy. The article below will tell you why DLP projectors struggle with creating a comparable level of image quality.
It’s like a set of blinds in your household for your bedroom window. By twisting a rod you can turn the shutters open or closed, depending on if you want to let light in or not. And that is exactly how an LCD projector behaves. 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 formed of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the point when the projector is switched on to when the picture reaches your screen is extremely significant to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by dividing it into red, blue and green components, by three mirrors which project the coloured light to 3 different LCD panels. The 3 LCD panels cast 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. A significant point to understad about LCD projectors is that all three colours are delivered onto your projector screen all at the same time. The way a DLP projector works is vastly different and even the way an image comes out 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 approach to creating an image casts a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to create the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s eyes will then combine each coloured element of the image into a single full image. From LCD projectors, all colours are available all the time to offer the best brightness and spectacular colour accuracy. In DLP, just one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP designers have placed a white segment into the colour wheel to improve overall brightness, but this further damages colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and therefore must be superior. For those who do not know, 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 possess high contrast specifications compared to many LCD projectors. At one glance, this can seem to be an advantage, however, in truth, the true black level is determined by the ambient light in the room while the projector is being utilised. Do not be duped by contrast specifications on websites and in brochures.
When the content you plan to see includes moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector creates 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 problem because the colours are sent at the same time. DLP developers have come up with 3DLP solutions using 3 chips to fix the colour break up problem, but the price of these projectors make them hardly practical for the majority of businesses and consumers.
Another variance between LCD and DLP is how they compensate for the refractive qualities of light. Take yourself back to high school science, and they taught you how the different colours of light refract varied amounts when projected through the same lens. The downside 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 different and refract light in a different way. Usually with a DLP projector, some extra yellow colour will appear above and some extra blue will appear below an image containing 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 a separate LCD panels.
The isolated veritable plus (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to portability and cannot be traded off against the image plusses of LCD projectors. If overall picture quality is vital to you, then the decision is no-brainer. Choose an LCD projector! LCD projectors will constantly produce bright, colourful images with fewer image mistakes. If you desire to learn more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any more questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online shop for projectors. Brisbane based, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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