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The most typical question that is asked when buying a new projector for the home, office, or classroom is: should I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most common projector imaging technologies. With so many company brands and different types available, it can be overwhelming for the buyer to make a decision between these technologies. The fact is that LCD projectors provide far superior image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with projecting a similar grade of image quality.

Visualise a set of blinds in your room on your bedroom window. By pulling on a rod you can make the shutters open or closed, depending on if you want to let light in or not. This is exactly how an LCD projector works. Each pixel works like a unique shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is made up 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 turns on to when the picture reaches your screen is vitally significant for image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by splitting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 separate LCD panels. The 3 LCD panels make the elements of the image by processing each pixel on and off. The pixels are then combined in a glass prism to send the projector image. Something to realise about LCD projectors is that all three colours are delivered onto your wall at the same time. The way a DLP projector runs is widely different and even the produced image shows up is not the same. With DLP, white light from the lamp is projected through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of projecting an image forms 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 sent in sequence on the screen, one colour at a time. The viewer’s eye will then put together each coloured element of the image into the single whole image. With LCD projectors, all colours are available all the time to create the highest brightness and superb colour accuracy. In DLP, only one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some DLP designers have placed a white segment into the colour wheel to improve all over brightness, but this also damages colour accuracy.

I find in forums all the time that DLP gives a higher contrast ratio and therefore must be superior. For those who are unsure, 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 projector is able to produce. DLP projectors do possess high contrast specifications in comparison to the majority of LCD projectors. Initially, this can seem to be a benefit, however, in the real world, the true black level is determined by the ambient light in the room while the projector is being utilised. Do not be fooled by contrast specifications on websites and in brochures.

When the content you are trying to project includes moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most typical artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable 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 problem because the colours are projected simultaneously. DLP designers have developed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the cost of these projectors make them not practical for the large part of businesses and consumers.

Another variance between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and they taught you how various colours of light refract different amounts when passing through the same lens. The problem with DLP projectors is that they use the one same panel for 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 spill of yellow colour will come through above and some blue will appear below an image as simple as a straight black line. In building LCD projectors can be fixed to remove these effects on the projected image, because each colour is projected on separate LCD panels.

The sole veritable plus (excluding price) with going with a DLP projector is its smaller size and weight. However, this is only relevant with regard to portability and must be traded off against the image superiority of LCD projectors. If the outcome of the picture quality is vital to you, then the choice is easy. Choose an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image imperfections. If you need to learn more about LCD technology in more detail, have a look at this fabulous resource website: Explore 3LCD. If you have any other questions, visit Projector Central and send me an email.

Jonathan King is the sales and marketing manager for Projector Central, Australia’s leading online retailer for projectors. Based in Brisbane, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.