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The most common question asked when looking for a new projector for the home, office, or classroom is: would I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and different types available, it can be confusing for clients to pick between those technologies. The fact is that LCD projectors provide better image quality and colour accuracy. The next part of this article will explain why DLP projectors struggle with reproducing an equal grade of image quality.

It’s like a set of blinds in your room on your bedroom window. By a twist of a rod you can turn the shutters open or closed, depending on if you want to let light in or not. This is exactly how an LCD projector behaves. Each pixel operates like a unique shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as 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 switches on to when the content reaches your screen is ultimately important 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 transfer 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 simultaneously processed in a glass prism to create the projector image. A significant point to understad about LCD projectors is that all three colours are sent onto your projected surface all at the same time. The way a DLP projector operates is very different and even the produced image shows up is not the same. With DLP, white light from the lamp is projected through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of projecting an image creates a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to produce the image elements. The elements of the image are displayed 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 total image. In LCD projectors, all colours are available all the time to create the highest brightness and spectacular colour accuracy. In DLP, just one colour is available at once, causing lower colour brightness and accuracy. Some DLP designers have put a white segment for the colour wheel to improve all over brightness, but this goes and detracts from colour accuracy.

I hear in forums all the time that DLP offers a higher contrast ratio and ergo must be better quality. 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 system is able to produce. DLP projectors do have high contrast specifications when compared to a majority of LCD projectors. At one glance, this seems to be a benefit, however, in real life, the true black level is determined by the ambient light in the room while the projector is in use. Do not be duped by contrast specifications on websites and in brochures.

When the content you want to project needs moving images, DLP projection technology also has image errors, or ‘artifacts’. The most commonplace artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because every colour is delivered simultaneously. DLP builders have formed 3DLP solutions using 3 chips to resolve the colour break up issue, but the price of these projectors make them almost impossible for most businesses and consumers.

Another point of difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and recall how the various colours of light refract various amounts when shone through the same lens. The problem with DLP projectors is that they use the one same panel for the same lens to project Red, Blue and Green. All 3 colours are different and refract light at different levels. Most of the time with a DLP projector, a superfluous yellow colour will come up above and some blue will appear below an image containing something as simple as a lone black line. While being built LCD projectors can be set to take away these effects on the projected image, as each colour is refracted on a separate LCD panels.

The only actual advantage (excluding price) with picking a DLP projector is its smaller size and weight. However, this is only relevant to transporting the device and cannot be traded off against the image plusses of LCD projectors. If resulting picture quality is vital to you, then the answer is easy. Take an LCD projector! LCD projectors will definitely produce bright, colourful images with fewer image mistakes. If you desire to learn more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any persisting questions, go to 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 serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.

This entry was posted on Monday, July 19th, 2010 at 1:35 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.