Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when buying 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, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many different brands and different models available, it can be challenging for consumers to make a decision between the two technologies. Ultimately LCD projectors have far superior image quality and colour accuracy. The article below explains why DLP projectors struggle with reproducing a comparable standard of image quality.
Visualise a set of blinds in your home for your bedroom window. By pulling a rod you can turn the shutters open or closed, according to whether you want to let light in or not. Such is exactly how an LCD projector works. Each pixel functions like a single shutter on a set of blinds to either send light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the point when the projector is switched on to when the picture reaches your screen is extremely significant with regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by splitting it into red, blue and green components, by three mirrors which direct the coloured light to 3 individual LCD panels. The 3 LCD panels form the elements of the image by turning each pixel on and off. The pixels are then projected in a glass prism to create the projector image. A significant point to know about LCD projectors is that all three colours are delivered onto your screen all at once. The way a DLP projector functions is widely different and even the final product of how an image shows up is not the same. With DLP, white light from the lamp is directed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of creating an image forms a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to form the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s eyes will then pull together each coloured element of the image into a complete image. With LCD projectors, all colours are available all the time to deliver the top level of brightness and fantastic colour accuracy. In DLP, just one colour is available at once, and so causing lower colour brightness and accuracy. Some DLP manufacturers have added a white segment into the colour wheel to improve brightness overall, but this then damages colour accuracy.
I find in forums all the time that DLP provides a higher contrast ratio and ergo must be better. For those 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 technology is capable of producing. DLP projectors do possess high contrast specifications compared to the majority of LCD projectors. At a glance, this can seem to be a plus, however, in truth, the true black level is determined by the ambient light in the room in which the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.
When the content you are trying to view has moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most often seen 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 up between the time red, blue and green colours are projected. LCD projectors do not have this disadvantage because all the colours are delivered with the others. DLP manufacturers have formed 3DLP solutions using 3 chips to fix the colour break up error, but the price tag of these projectors make them almost impossible for most businesses and consumers.
Another differentiation between LCD and DLP is how they match the balance for the refractive qualities of light. Take yourself back to high school science, and remember how different colours of light refract varied amounts when passing through the same lens. The disadvantage 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 different and refract light in a different way. Most of the time with a DLP projector, some extra yellow colour will come through above and some extra blue will come through below something as simple as a lone black line. In manufacturing LCD projectors can be fixed to minimize these effects on the projected image, because each colour is processed on isolated LCD panels.
The one true benefit (excluding price) with buying a DLP projector is its smaller total size and weight. However, this is only relevant for transport and cannot be traded off against the image benefits of LCD projectors. If resulting picture quality is vital to you, then the solution is easy. Choose an LCD projector! LCD projectors will always show bright, colourful images with fewer image imperfections. If you desire to learn more about LCD technology in more detail, see 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 with Projector Central, Australia’s leading online shop for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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