The most typical question asked when purchasing a new projector for the home, office, or classroom is: should I purchase an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most popular projector imaging technologies. With so many company brands and types available, it can be challenging for the buyer to choose between these technologies. Ultimately LCD projectors provide far superior image quality and colour accuracy. The following article explains why DLP projectors struggle with projecting the same level of image quality.

Think of a set of blinds in your home on your bedroom window. By pulling on a rod you can turn the shutters open or closed, according to if you want to let light in or not. And that is exactly how an LCD projector operates. Each pixel functions like a single shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the professionals like to call them. Each pixel element functions to either reflect light or block it.

How the light source is processed from when the projector turns on to when the picture reaches your screen is extremely significant with regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 stand alone LCD panels. The 3 LCD panels cast the elements of the image by shining each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. Something to remember about LCD projectors is that all three colours are projected onto your screen simultaneously. The way a DLP projector works is vastly different and even the way an image looks is not the same. With DLP, white light from the lamp is sent 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 described above reflect the coloured light on the pixels to create 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 pull together each coloured element of the image into the complete image. Using LCD projectors, all colours are available all the time to deliver the highest brightness and great colour accuracy. In DLP, just one colour is available at a time, causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment into the colour wheel to improve general brightness, but this also damages colour accuracy.

I read in forums all the time that DLP gives a higher contrast ratio and ergo must be better. For those who are unaware, 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 producing. DLP projectors do have high contrast specifications as compared to many LCD projectors. At a glance, this seems to be an advantage, however, in truth, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be duped by contrast specifications on websites and in brochures.

When the content you wish to see needs moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most often seen artifact that a DLP projector shows with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change up between the time red, blue and green colours are pulled up. LCD projectors do not have this downside because every colour is processed at once. DLP builders have developed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the price of these projectors make them hardly practical for many businesses and consumers.

Another difference between LCD and DLP is how they balance for the refractive qualities of light. Remember back to high school science, and recall how the different colours of light refract different amounts when directed 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 different and refract light in different ways. Usually with a DLP projector, some yellow colour will show above and some blue will come up below an image containing something as simple as a lone black line. In building LCD projectors can be adjusted to reduce these effects on the projected image, because each colour is projected on a separate LCD panels.

The isolated true benefit (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 crucial to you, then the answer is easy. Take an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image imperfections. If you need to know more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any additional questions, go to Projector Central and send me an email.

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