The typical question asked when purchasing a new projector for the home, office, or classroom is: would I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many brands and types available, it can be challenging for the buyer to make a choice between the two technologies. Ultimately LCD projectors give superior image quality and colour accuracy. The next paragraph explains why DLP projectors struggle with bringing up the same level of image quality.

Imagine a set of blinds in your home over your bedroom window. With the twist of a rod you can make the shutters open or closed, according to whether you want to let light in or not. 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 made up of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from when the projector turns on to when the content reaches your screen is vitally significant for image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by dividing it into red, blue and green components, by three mirrors which transfer the coloured light to 3 separate LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. A significant point to understad about LCD projectors is that all three colours are projected onto your projected surface simultaneously. The way a DLP projector functions is widely different and even the way an image comes out 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 forming an image requires 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 displayed in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into the single full image. In LCD projectors, all colours are available all the time to offer the best brightness and fantastic colour accuracy. In DLP, only one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some designers have included a white segment into the colour wheel to improve brightness generally, but this goes and lessens colour accuracy.

I hear in forums all the time that DLP provides a higher contrast ratio and therefore must be superior quality. For those uncertain, 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 have high contrast specifications compared to most LCD projectors. Initially, this appears to be a benefit, however, in truth, the true black level is determined by the ambient light in the room where the projector is being utilised. 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 imperfections, or ‘artifacts’. The most common artifact that a DLP projector forms with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because all the colours are delivered simultaneously. DLP designers have created 3DLP solutions using 3 chips to answer the colour break up error, but the expense of these projectors make them impractical 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 remember when they taught you how different colours of light refract different amounts when projected through the same lens. The problem with DLP projectors is that they utilise the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in a different way. Most of the time with a DLP projector, a superfluous yellow colour will come up above and an extra blue will come up below an image as simple as a lone black line. In building LCD projectors can be adapted to remove these effects on the projected image, as each colour is processed on isolated LCD panels.

The one real advantage (excluding price) with deciding on a DLP projector is its overall smaller size and weight. However, this is only relevant to mobility and cannot be traded off against the image superiority of LCD projectors. If resulting picture quality is important to you, then the answer is easy. Choose an LCD projector! LCD projectors will always produce bright, colourful images with fewer image mistakes. If you wish to ask more about LCD technology in more detail, have a look at this fantastic resource website: Explore 3LCD. If you have any persisting questions, visit Projector Central and send me an email.

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