The common question that is asked when purchasing a new projector for the home, office, or classroom is: would I purchase 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 different brands and types available, it can be difficult for the buyer to make a choice between the two technologies. Ultimately LCD projectors provide better image quality and colour accuracy. The next paragraph tells you why DLP projectors struggle with reproducing the same standard of image quality.

Think of a set of blinds in your house covering your bedroom window. By pulling on a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And that is exactly how an LCD projector operates. Each pixel works like a single shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as professionals 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 image reaches your screen is extremely important to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by dividing it into red, blue and green components, by three mirrors which transfer 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 simultaneously processed in a glass prism to form the projector image. A significant point to know about LCD projectors is that all three colours are directed onto your projected surface all at the same time. The way a DLP projector functions is vastly different and even the way an image shows up is not the same. With DLP, white light from the lamp is processed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making 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 form 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 put together each coloured element of the image into a full image. With LCD projectors, all colours are available all the time to form the best brightness and spectacular colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some manufacturers have put a white segment into the colour wheel to improve general brightness, but this goes and degrades colour accuracy.

I read in forums all the time that DLP provides a higher contrast ratio and therefore 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 system is capable of producing. DLP projectors do have high contrast specifications when compared to the majority of LCD projectors. Initially, this appears to be a benefit, however, in the real world, the true black level is determined by the ambient light in the room in which the projector is in use. Do not be duped by contrast specifications on websites and in brochures.

When the content you wish to bring to life has moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most commonplace artifact that a DLP projector creates with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change position between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because all the colours are projected at the same time. DLP manufacturers have developed 3DLP solutions using 3 chips to resolve the colour break up problem, but the price tag of these projectors make them not practical for most businesses and consumers.

Another point of difference between LCD and DLP is how they compensate for the refractive qualities of light. Take yourself back to high school science, and recall when they taught you how various colours of light refract different amounts when passing through the same lens. The downside with DLP projectors is that they have the one same panel for the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Usually with a DLP projector, some yellow colour will show above and some blue will come through below something as simple as a straight black line. In building LCD projectors can be adjusted to remove these effects on the projected image, because each colour is projected on separate LCD panels.

The sole real buy point (excluding price) with going with a DLP projector is its smaller size and weight. However, this is only relevant with regard to portability and cannot be traded off against the image advantages of LCD projectors. If overall picture quality is crucial to you, then the solution is simple. Choose an LCD projector! LCD projectors will constantly produce bright, colourful images with fewer image blips. If you desire to find out more about LCD technology in more detail, have a look at this tremendous resource website: Explore 3LCD. If you have any additional questions, visit Projector Central and send me an email.

Jonathan King is the sales and marketing manager at Projector Central, Australia’s top online provider for projectors. Based in Brisbane, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.