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The most typical question that is asked when purchasing a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many company brands and types available, it can be difficult for the buyer to pick between those technologies. Ultimately LCD projectors provide better image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with creating a similar standard of image quality.

Imagine a set of blinds in your house for your bedroom window. With the twist of a rod you can make the shutters open or closed, according to if you want to let light in or not. And this is exactly how an LCD projector functions. Each pixel operates like a unique shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as the pros like to call them. Each pixel element works to either reflect light or block it.

How the light source is processed from the point when the projector switches on to when the picture reaches your screen is vitally important with regard to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by separating 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 form 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. A significant point to know about LCD projectors is that all three colours are directed onto your screen all at the same time. The way a DLP projector operates is widely different and even the way an image shows up is not the same. With DLP, white light from the lamp is sent 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 mentioned above reflect the coloured light on the pixels to create the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s vision will then put together each coloured element of the image into the single whole image. Using LCD projectors, all colours are available all the time to offer top brightness and spectacular colour accuracy. In DLP, only one colour is available at a time, resulting in lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment for the colour wheel to improve overall brightness, but this also lessens colour accuracy.

I find in forums all the time that DLP offers a higher contrast ratio and thus must be superior quality. For those who are unsure, 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 technology is able to produce. DLP projectors do have high contrast specifications when compared to the majority of LCD projectors. Initially, this must be an advantage, however, in real life, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be fooled by contrast specifications on websites and in brochures.

When the content you plan to bring to life has moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most common artifact that a DLP projector shows 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 projected. LCD projectors do not have this downside because all colours are delivered at the same time. DLP builders have developed 3DLP solutions using 3 chips to fix the colour break up error, but the expense of these projectors make them impractical for most businesses and consumers.

Another point of difference between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and remember how different colours of light refract different amounts when shone through the same lens. The disadvantage 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 at different levels. Generally with a DLP projector, some yellow colour will show above and a superfluous blue will come through below an image as simple as a straight black line. In manufacturing LCD projectors can be adapted to reduce these effects on the projected image, as each colour is directed on isolated LCD panels.

The only actual benefit (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant to mobility and needs to be traded off against the image plusses of LCD projectors. If resulting picture quality is important to you, then the decision is easy. Go for an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image mistakes. If you need to know more about LCD technology in more detail, have a look at this fantastic resource website: Explore 3LCD. If you have any more questions, visit Projector Central and send me an email.

Jonathan King is the sales and marketing manager of Projector Central, Australia’s premier online provider for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.