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The typical question that is asked when acquiring a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many brands and models available, it can be challenging for the buyer to decide between these technologies. The fact is that LCD projectors provide far better image quality and colour accuracy. The article below will tell you why DLP projectors struggle with creating the same grade of image quality.

It’s like a set of blinds in your house covering your bedroom window. With the twist of a rod you can make the shutters open or closed, according to whether you want to let light in or not. That is exactly how an LCD projector works. Each pixel works like a single shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from when the projector switches on to when the picture reaches your screen is absolutely important 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 project the coloured light to 3 separate LCD panels. The 3 LCD panels create the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. An important point to know about LCD projectors is that all three colours are sent onto your wall simultaneously. The way a DLP projector works is totally different and even the final product of how an image comes out 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 method of projecting an image creates a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to produce the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into the complete image. In LCD projectors, all colours are available all the time to form the highest brightness and spectacular colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some developers have put a white segment in the colour wheel to improve overall brightness, but this then degrades colour accuracy.

I read in forums all the time that DLP gives a higher contrast ratio and thus must be superior 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 machine is capable of. DLP projectors do have high contrast specifications compared to the majority of LCD projectors. At one glance, this appears to be a plus, however, in real life, the true black level is determined by the ambient light in the room when the projector is being utilised. Do not be tricked by contrast specifications on websites and in brochures.

When the content you plan to project needs moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most typical 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 up between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because all colours are processed simultaneously. DLP designers have developed 3DLP solutions using 3 chips to fix the colour break up artifacts, but the price of these projectors make them impractical for the majority of businesses and consumers.

Another point of difference between LCD and DLP is how they match the balance for the refractive qualities of light. Take yourself back to high school science, and remember how different colours of light refract varied amounts when passing through the same lens. The disadvantage with DLP projectors is that they use the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Generally with a DLP projector, a spill of yellow colour will show above and a superfluous blue will appear below an image of something as simple as a straight black line. While being built LCD projectors can be adjusted to reduce these effects on the projected image, because each colour is refracted on its own LCD panels.

The sole actual benefit (excluding price) with buying a DLP projector is its smaller size and weight. However, this is only relevant for transporting the device and needs to be traded off against the image superiority of LCD projectors. If the result of the picture quality is important to you, then the decision is a no-brainer. Choose an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image imperfections. If you desire to find out more about LCD technology in more detail, check out this fabulous resource website: Explore 3LCD. If you have any further 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.