The typical question customers ask when buying a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and different types available, it can be confusing for clients to choose between these technologies. The simple fact of the matter is that LCD projectors offer far superior image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with reproducing the same grade of image quality.
Visualise a set of blinds in your home on your bedroom window. By a twist of a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. And that is exactly how an LCD projector works. Each pixel functions like a single shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from when the projector is switched on to when the content reaches your screen is vitally significant with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by separating it into red, blue and green components, by three mirrors which direct the coloured light to 3 separate LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then combined in a glass prism to deliver the projector image. Something to realise about LCD projectors is that all three colours are sent onto your projected surface at the same time. The way a DLP projector works is widely different and even how an image looks is not the same. With DLP, white light from the lamp is projected through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of forming an image casts a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to construct the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eye will then pull together each coloured element of the image into a full image. With LCD projectors, all colours are available all the time to offer the top level of brightness and fantastic colour accuracy. In DLP, just one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP designers have put a white segment into the colour wheel to improve general brightness, but this goes and degrades colour accuracy.
I find in forums all the time that DLP has a higher contrast ratio and as such must be superior quality. 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 projector is capable of producing. DLP projectors do provide high contrast specifications compared to a majority of LCD projectors. At one glance, this can seem to be a plus, however, in real life, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you want to view needs moving images, DLP projection technology can also create image errors, or ‘artifacts’. The most common artifact that a DLP projector displays with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change position between the time red, blue and green colours are shone. LCD projectors do not have this characteristic because all colours are sent at once. DLP manufacturers have developed 3DLP solutions using 3 chips to fix the colour break up error, but the cost of these projectors make them not practical for most businesses and consumers.
Another point of difference between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and remember when they taught you how the different colours of light refract various amounts when projected through the same lens. The problem with DLP projectors is that they have the one same panel and 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 yellow colour will appear above and some extra blue will come up below an image of something as simple as a lone black line. In manufacturing LCD projectors can be fixed to reduce these effects on the projected image, because each colour is directed on separate LCD panels.
The one true advantage (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant to transporting the device and needs to be traded off against the image plusses of LCD projectors. If resulting picture quality is important to you, then the answer is easy. Go with an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image imperfections. If you need to learn more about LCD technology in more detail, see this fabulous resource website: Explore 3LCD. If you have any more questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s premier online retailer for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.