The most typical question asked when purchasing a new projector for the home, office, or classroom is: do I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and types available, it can be difficult for consumers to make a decision between both technologies. The fact is that LCD projectors provide far better image quality and colour accuracy. The following article will explain why DLP projectors struggle with creating a comparable standard of image quality.
Think of a set of blinds in your house over your bedroom window. By a twist of a rod you can make the shutters open or closed, according to if you want to let light in or not. This is exactly how an LCD projector works. Each pixel operates like its own shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as the 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 image reaches your screen is absolutely significant 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 direct 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 simultaneously processed in a glass prism to form the projector image. A significant point to understad about LCD projectors is that all three colours are directed 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 turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of forming 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 form the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s eye will then put together each coloured element of the image into a single full image. From LCD projectors, all colours are available all the time to form the top level of brightness and great colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some manufacturers have added a white segment into the colour wheel to improve overall brightness, but this also damages colour accuracy.
I read in forums all the time that DLP has a higher contrast ratio and as such 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 projector is capable of. DLP projectors do have high contrast specifications when compared to most LCD projectors. Initially, this must be an advantage, however, in the real world, the true black level is determined by the ambient light in the room where the projector is being used. Do not be fooled by contrast specifications on websites and in brochures.
When the content you are trying to see has moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this disadvantage because all the colours are projected simultaneously. DLP manufacturers have formed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the price tag of these projectors make them almost impossible for the large part of businesses and consumers.
Another difference between LCD and DLP is how they balance for the refractive qualities of light. Remember back to high school science, and recall when they taught you how different colours of light refract different amounts when projected 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. Most of the time with a DLP projector, a superfluous yellow colour will be projected above and an extra blue will show below an image of something as simple as a single black line. While being built LCD projectors can be fixed to minimize these effects on the projected image, as each colour is projected on its own LCD panels.
The only real buy point (excluding price) with taking a DLP projector is its smaller total size and weight. However, this is only relevant in regard to portability and needs to be traded off against the image benefits of LCD projectors. If resulting picture quality is crucial to you, then the solution is a no-brainer. Choose an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you want to find out more about LCD technology in more detail, have a gander at this tremendous 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 for Projector Central, Australia’s number one online provider for projectors. Brisbane-based, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.