The most common question asked when purchasing a new projector for the home, office, or classroom is: will I buy an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and models available, it can be overwhelming for the buyer to decide between the two technologies. The fact is that LCD projectors provide far superior image quality and colour accuracy. The next part of this article explains why DLP projectors struggle with reproducing an equal rate of image quality.

Think of a set of blinds in your home on your bedroom window. By twisting 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 shine 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 functions to either reflect light or block it.

How the light source is processed from when the projector is turned on to when the picture reaches your screen is vitally significant with regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by switching each pixel on and off. The pixels are then combined in a glass prism to form the projector image. An important point to understad about LCD projectors is that all three colours are directed onto your projector screen at once. The way a DLP projector works is totally 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 approach to making 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 produce the image elements. The elements of the image are projected 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 whole image. With LCD projectors, all colours are available all the time to deliver the top level of brightness and spectacular colour accuracy. In DLP, only one colour is available at a time, and so causing lower colour brightness and accuracy. Some DLP designers have placed a white segment in the colour wheel to improve brightness overall, but this further detracts from colour accuracy.

I read in forums all the time that DLP offers 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 technology is capable of producing. DLP projectors do offer high contrast specifications compared to a majority of LCD projectors. Initially, this must be a plus, however, in truth, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be fooled by contrast specifications on websites and in brochures.

When the content you wish to see has moving images, DLP projection technology also creates image marks, or ‘artifacts’. The most typical 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 shone. LCD projectors do not have this characteristic because all the colours are sent simultaneously. DLP developers have formed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the cost of these projectors make them hardly practical for the majority of businesses and consumers.

Another differentiation between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and recall how different colours of light refract various amounts when directed through the same lens. The downside with DLP projectors is that they utilise the one same panel for the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light differently. Often with a DLP projector, a spill of yellow colour will be projected above and some blue will show below an image containing something as simple as a single black line. In manufacturing LCD projectors can be fixed to take away these effects on the projected image, as each colour is refracted on a separate LCD panels.

The isolated real benefit (excluding price) with going with a DLP projector is its smaller total size and weight. However, this is only relevant to transport and has to be traded off against the image benefits of LCD projectors. If the result of the picture quality is vital to you, then the choice is simple. Choose an LCD projector! LCD projectors will always make bright, colourful images with fewer image imperfections. If you wish to find out more about LCD technology in more detail, check out this fabulous 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 provider for projectors. Brisbane-based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.

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