CTO Blog

The typical question asked when looking for a new projector for the home, office, or classroom is: will I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and types available, it can be confusing for clients to make a choice between those technologies. The simple fact of the matter is that LCD projectors give better image quality and colour accuracy. The next part of this article will explain why DLP projectors struggle with reproducing a comparable rate of image quality.

Think of a set of blinds in your household for your bedroom window. By a twist of a rod you can make the shutters open or closed, according to if you want to let light in or not. Such is exactly how an LCD projector behaves. 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 operates to either reflect light or block it.

How the light source is processed from the point when the projector is turned on to when the picture reaches your screen is extremely significant in regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by separating it into red, blue and green components, by three mirrors which project the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by shining each pixel on and off. The pixels are then simultaneously processed in a glass prism to form the projector image. Something important to understad about LCD projectors is that all three colours are sent onto your projected surface simultaneously. The way a DLP projector works is widely different and even the way an image looks 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 forming 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 form the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into the single complete image. Using LCD projectors, all colours are available all the time to form top brightness and spectacular colour accuracy. In DLP, only one colour is available at once, causing lower colour brightness and accuracy. Some developers have included a white segment into the colour wheel to improve general brightness, but this further lessens colour accuracy.

I hear in forums all the time that DLP has a higher contrast ratio and ergo must be better quality. For those who don’t 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 technology is capable of. DLP projectors do offer high contrast specifications in comparison to most LCD projectors. At a glance, this seems 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 being used. Do not be tricked by contrast specifications on websites and in brochures.

When the content you want to bring to life has moving images, DLP projection technology also creates image marks, or ‘artifacts’. The most commonplace artifact that a DLP projector forms with moving images is colour break up. Colour break up is inherent in DLP systems because moving images keep changing between the time red, blue and green colours are projected. LCD projectors do not have this disadvantage because all colours are projected at the same time. DLP manufacturers have created 3DLP solutions using 3 chips to resolve the colour break up problem, but the expense of these projectors make them hardly practical for the majority of businesses and consumers.

Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Remember back to high school science, and they taught you how the different colours of light refract varied amounts when directed through the same lens. The problem with DLP projectors is that they have the one same panel with the same lens to project Red, Blue and Green. All 3 colours are different and refract light at different levels. Usually with a DLP projector, a spill of yellow colour will come through above and a spill of blue will appear below an image of something as simple as a straight black line. In building LCD projectors can be set to reduce these effects on the projected image, as each colour is projected on a separate LCD panels.

The only true plus (excluding price) with taking a DLP projector is its smaller size and weight. However, this is only relevant for mobility and must be traded off against the image plusses of LCD projectors. If resulting picture quality is important to you, then the decision is simple. Take an LCD projector! LCD projectors will always show bright, colourful images with fewer image mistakes. If you need to ask more about LCD technology in more detail, check out this tremendous resource website: Explore 3LCD. If you have any further questions, jump onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager for Projector Central, Australia’s top online shop for projectors. Brisbane based, Projector Central has served Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.