Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question heard 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, an acronym for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and different models available, it can be overwhelming for the buyer to choose between both technologies. Ultimately LCD projectors provide better image quality and colour accuracy. The article below will tell you why DLP projectors struggle with creating the same level of image quality.
Imagine a set of blinds in your home over your bedroom window. By a twist of a rod you can make the shutters open or closed, depending on if you want to let light in or not. And this is exactly how an LCD projector works. Each pixel operates like a unique shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the point at which the projector is switched on to when the picture reaches your screen is vitally significant 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 project the coloured light to 3 stand alone LCD panels. The 3 LCD panels make the elements of the image by turning each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. A significant point to remember about LCD projectors is that all three colours are sent onto your wall all at once. The way a DLP projector operates is widely different and even 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 approach to creating an image casts a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to construct the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eyes will then draw each coloured element of the image into a whole image. Using LCD projectors, all colours are available all the time to deliver the highest brightness and fantastic colour accuracy. In DLP, only one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some DLP developers have included a white segment into the colour wheel to improve general brightness, but this further damages colour accuracy.
I see in forums all the time that DLP offers a higher contrast ratio and as such must be better quality. 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 system is capable of producing. DLP projectors do possess high contrast specifications in comparison to most LCD projectors. At one glance, this seems to be a plus, however, in real life, the true black level is determined by the ambient light in the room in which the projector is used. Do not be fooled by contrast specifications on websites and in brochures.
When the content you plan to view needs moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most typical 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 up between the time red, blue and green colours are pulled up. LCD projectors do not have this disadvantage because the colours are sent at once. DLP developers have formed 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the price tag of these projectors make them almost impossible for many businesses and consumers.
Another differentiation between LCD and DLP is how they balance for the refractive qualities of light. Jump back to high school science, and recall when they taught you how the various colours of light refract different amounts when shone through the same lens. The downfall 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 not the same and refract light in different ways. Most of the time with a DLP projector, a spill of yellow colour will be projected above and some extra blue will come up below an image of something as simple as a single black line. During manufacturing LCD projectors can be adapted to take away these effects on the projected image, because each colour is directed on a separate LCD panels.
The only true plus (excluding price) with going with a DLP projector is its overall smaller size and weight. However, this is only relevant to portability and cannot be traded off against the image benefits of LCD projectors. If the result of the picture quality is crucial to you, then the solution is easy. Take an LCD projector! LCD projectors will always make bright, colourful images with fewer image mistakes. If you desire to learn more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any additional questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s number one online retailer for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
