Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question that is asked when acquiring a new projector for the home, office, or classroom is: would I purchase an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and types available, it can be confusing for consumers to choose between these technologies. Ultimately LCD projectors give better image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with projecting the same level of image quality.
Visualise a set of blinds in your house covering your bedroom window. By a twist of a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And this is exactly how an LCD projector functions. Each pixel functions like an individual 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 experts like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the time the projector is turned on to when the picture reaches your screen is vitally significant for image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by dividing it into red, blue and green components, by three mirrors which send the coloured light to 3 different 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 create the projector image. Something important to remember about LCD projectors is that all three colours are projected onto your screen all at the same time. The way a DLP projector functions is vastly different and even how an image comes out is not the same. With DLP, white light from the lamp is sent through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of creating an image requires a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to produce the image elements. The elements of the image are sent 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 total image. With LCD projectors, all colours are available all the time to deliver high brightness and great colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment into the colour wheel to improve general brightness, but this further damages colour accuracy.
I hear in forums all the time that DLP gives a higher contrast ratio and as such must be superior quality. For those who are 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 projector is capable of producing. DLP projectors do offer high contrast specifications when compared to most LCD projectors. Initially, this can seem to be an advantage, however, in truth, the true black level is determined by the ambient light in the room when the projector is used. Do not be tricked by contrast specifications on websites and in brochures.
When the content you are trying to project needs 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 unavoidable in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this downside because every colour is processed at the same time. DLP manufacturers have come up with 3DLP solutions using 3 chips to answer the colour break up artifacts, but the price tag of these projectors make them almost impossible for the majority of businesses and consumers.
Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Remember back to high school science, and recall how different colours of light refract various amounts when passing 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 not the same and refract light in a different way. Usually with a DLP projector, some extra yellow colour will be projected above and a superfluous blue will come up below an image of something as simple as a single black line. During manufacturing LCD projectors can be set to minimize these effects on the projected image, as each colour is processed on separate LCD panels.
The only veritable plus (excluding price) with going with a DLP projector is its overall smaller size and weight. However, this is only relevant to mobility and needs to be traded off against the image advantages of LCD projectors. If the result of the picture quality is important to you, then the solution is no-brainer. Go for an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you need to learn more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s leading online shop for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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