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The most typical question heard when acquiring 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 models available, it can be overwhelming for the buyer to make a choice between these technologies. The fact is that LCD projectors give far better image quality and colour accuracy. The following article explains why DLP projectors struggle with projecting a comparable standard of image quality.

It’s like a set of blinds in your home for your bedroom window. By pulling on a rod you can have the shutters open or closed, depending on if you want to let light in or not. And that is exactly how an LCD projector functions. Each pixel works like a unique shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as the pros like to call them. Each pixel element works to either reflect light or block it.

How the light source is processed from the time the projector turns on to when the image reaches your screen is vitally significant with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by splitting it into red, blue and green components, by three mirrors which send 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 meshed in a glass prism to send the projector image. A point to understad about LCD projectors is that all three colours are sent onto your wall at once. The way a DLP projector works is totally different and even the final product of how an image looks is not the same. With DLP, white light from the lamp is sent through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method 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 construct the image elements. The elements of the image are projected 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 the single whole image. From LCD projectors, all colours are available all the time to create the top level of brightness and spectacular colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some developers have placed a white segment in the colour wheel to improve brightness generally, but this further damages colour accuracy.

I find in forums all the time that DLP offers a higher contrast ratio and as such 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 system is capable of. DLP projectors do provide high contrast specifications in comparison to many LCD projectors. At one glance, this appears to be a benefit, however, in reality, the true black level is determined by the ambient light in the room in which the projector is utilised. Do not be fooled by contrast specifications on websites and in brochures.

When the content you are trying to bring to life needs moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most common artifact that a DLP projector shows with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change between the time red, blue and green colours are pulled up. LCD projectors do not have this characteristic because all colours are sent at once. DLP developers have formed 3DLP solutions using 3 chips to fix the colour break up artifacts, but the price of these projectors make them not practical for the large part of businesses and consumers.

Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and remember how different colours of light refract different amounts when projected through the same lens. The problem with DLP projectors is that they take the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously not the same and refract light differently. Often with a DLP projector, some yellow colour will come through above and some blue will appear below an image of something as simple as a single black line. During manufacturing LCD projectors can be fixed to minimize these effects on the projected image, because each colour is refracted on separate LCD panels.

The sole real buy point (excluding price) with going with a DLP projector is its smaller overall size and weight. However, this is only relevant with regard to portability and needs to be traded off against the image benefits of LCD projectors. If overall picture quality is crucial to you, then the solution is a no-brainer. Go for an LCD projector! LCD projectors will definitely make bright, colourful images with fewer image errors. If you wish to know more about LCD technology in more detail, have a look at this fantastic 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 of Projector Central, Australia’s premier online shop for projectors. Brisbane-based, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.

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