Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question that is asked when buying a new projector for the home, office, or classroom is: would I take an LCD projector or a DLP projector? LCD, which stands 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 clients to make a choice between those technologies. It comes down to the fact that LCD projectors have far better image quality and colour accuracy. The article below will tell you why DLP projectors struggle with reproducing a comparable grade of image quality.
It’s like a set of blinds in your room over your bedroom window. With the twist of a rod you can make the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector works. Each pixel functions like its own 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 experts 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 switches on to when the content reaches your screen is absolutely significant for 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 send the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by turning each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. Something to remember about LCD projectors is that all three colours are projected onto your screen at once. The way a DLP projector functions is very different and even the way an image shows up is not the same. With DLP, white light from the lamp is directed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way 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 produce the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s vision will then draw each coloured element of the image into the whole image. With LCD projectors, all colours are available all the time to create the best brightness and superb colour accuracy. In DLP, only one colour is available at once, causing lower colour brightness and accuracy. Some manufacturers have put a white segment in the colour wheel to improve brightness overall, but this then detracts from colour accuracy.
I see in forums all the time that DLP provides a higher contrast ratio and ergo must be superior quality. For those who do not 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 machine is able to produce. DLP projectors do have high contrast specifications when compared to the majority of LCD projectors. At a glance, this appears to be an advantage, however, in reality, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to project requires moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector displays with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this downside because every colour is delivered at the same time. DLP manufacturers have developed 3DLP solutions using 3 chips to answer the colour break up error, but the cost of these projectors make them almost impossible for the large part of businesses and consumers.
Another variance between LCD and DLP is how they make up for the refractive qualities of light. Take yourself back to high school science, and remember when they taught you how various colours of light refract different amounts when projected through the same lens. The downfall with DLP projectors is that they utilise the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in different ways. Most of the time with a DLP projector, some extra yellow colour will show above and some extra blue will show below something as simple as a single black line. During manufacturing LCD projectors can be adjusted to minimize these effects on the projected image, as each colour is refracted on separate LCD panels.
The one true advantage (excluding price) with taking a DLP projector is its smaller size and weight. However, this is only relevant for portability and needs to be traded off against the image advantages of LCD projectors. If resulting picture quality is vital to you, then the answer is simple. Go for an LCD projector! LCD projectors will always make bright, colourful images with fewer image mistakes. If you need to ask more about LCD technology in more detail, see this fantastic resource website: Explore 3LCD. If you have any other questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s top 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.