Australian Travel

The most typical question that is asked when purchasing a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many brands and different models available, it can be confusing for customers to pick between those technologies. Ultimately LCD projectors provide better image quality and colour accuracy. The next paragraph explains why DLP projectors struggle with projecting a comparable grade of image quality.

Imagine a set of blinds in your home covering your bedroom window. By pulling on a rod you can have the shutters open or closed, according to whether you want to let light in or not. And this is exactly how an LCD projector works. Each pixel works like an individual shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element works to either reflect light or block it.

How the light source is processed from when the projector is switched on to when the content 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 project the coloured light to 3 different LCD panels. The 3 LCD panels make the elements of the image by turning each pixel on and off. The pixels are then combined in a glass prism to deliver the projector image. Something important to know about LCD projectors is that all three colours are delivered onto your screen at once. The way a DLP projector operates is totally different and even the way an image looks 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 projecting an image casts 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 cast in sequence on the screen, one colour at a time. The viewer’s eyes will then put together each coloured element of the image into the single whole image. In LCD projectors, all colours are available all the time to form the best brightness and fantastic colour accuracy. In DLP, only one colour is available at a time, and so causing lower colour brightness and accuracy. Some designers have included a white segment for the colour wheel to improve all over brightness, but this also damages colour accuracy.

I read in forums all the time that DLP has a higher contrast ratio and ergo 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 able to produce. DLP projectors do possess high contrast specifications when compared to many LCD projectors. At first glance, this appears to be a benefit, however, in truth, the true black level is determined by the ambient light in the room when the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.

When the content you wish to view has moving images, DLP projection technology also has image marks, or ‘artifacts’. The most often seen artifact that a DLP projector displays with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images keep changing between the time red, blue and green colours are pulled up. LCD projectors do not have this characteristic because all the colours are sent simultaneously. DLP manufacturers have created 3DLP solutions using 3 chips to solve the colour break up issue, but the expense of these projectors make them not practical for most businesses and consumers.

Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Jump back to high school science, and remember how the different colours of light refract varied amounts when shone through the same lens. The problem with DLP projectors is that they use the one same panel with the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Often with a DLP projector, a superfluous yellow colour will be projected above and a superfluous blue will come up below an image containing something as simple as a lone black line. In building LCD projectors can be set to minimize these effects on the projected image, because each colour is processed on separate LCD panels.

The one real plus (excluding price) with taking a DLP projector is its overall smaller size and weight. However, this is only relevant to transporting the device and must be traded off against the image superiority of LCD projectors. If resulting picture quality is vital to you, then the solution is easy. Go for an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image errors. If you wish to learn more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any further questions, get onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager of Projector Central, Australia’s premier 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.