The typical question customers ask when acquiring a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and different types available, it can be difficult for clients to decide between these technologies. Ultimately LCD projectors provide far superior image quality and colour accuracy. The article below tells you why DLP projectors struggle with creating a comparable level of image quality.
Think of a set of blinds in your household over your bedroom window. By twisting a rod you can turn the shutters open or closed, according to whether you want to let light in or not. That is exactly how an LCD projector functions. Each pixel operates like an individual shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as the pros 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 turns on to when the image reaches your screen is vitally important to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by dividing it into red, blue and green components, by three mirrors which direct the coloured light to 3 different LCD panels. The 3 LCD panels make the elements of the image by switching each pixel on and off. The pixels are then combined in a glass prism to send the projector image. Something important to know about LCD projectors is that all three colours are directed onto your wall all at the same time. The way a DLP projector functions is vastly different and even the final product of how an image looks 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 method of creating an image requires a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to form the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eyes will then combine each coloured element of the image into a complete image. From LCD projectors, all colours are available all the time to form high brightness and superb colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some designers have added a white segment into the colour wheel to improve brightness generally, but this also damages colour accuracy.
I see in forums all the time that DLP gives a higher contrast ratio and therefore must be better quality. For those 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 machine is capable of. DLP projectors do offer high contrast specifications in comparison to most LCD projectors. At first glance, this must be a benefit, however, in real life, the true black level is determined by the ambient light in the room where the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you are trying to project needs moving images, DLP projection technology also has image errors, or ‘artifacts’. The most common 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 position between the time red, blue and green colours are pulled up. LCD projectors do not have this disadvantage because all colours are processed with the others. DLP developers have come up with 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the price of these projectors make them almost impossible for most businesses and consumers.
Another differentiation between LCD and DLP is how they balance for the refractive qualities of light. Take yourself back to high school science, and recall how the various colours of light refract various amounts when shone through the same lens. The downfall with DLP projectors is that they have 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 differently. Generally with a DLP projector, some extra yellow colour will come up above and a spill of blue will appear below an image containing something as simple as a lone black line. While being built LCD projectors can be adapted to take away these effects on the projected image, as each colour is processed on separate LCD panels.
The one real buy point (excluding price) with taking a DLP projector is its smaller size and weight. However, this is only relevant in regard to portability and must be traded off against the image advantages of LCD projectors. If overall picture quality is important to you, then the choice is a no-brainer. Go with an LCD projector! LCD projectors will always produce bright, colourful images with fewer image mistakes. If you wish 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 with Projector Central, Australia’s number one online store for projectors. Brisbane-based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.