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, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and models available, it can be confusing for the buyer to make a choice between these technologies. The fact is that LCD projectors offer far superior image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with reproducing the same level of image quality.
Imagine a set of blinds in your home over your bedroom window. By pulling a rod you can make the shutters open or closed, according to whether you want to let light in or not. Such is exactly how an LCD projector works. Each pixel works like an individual shutter on a set of blinds to either send light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as the professionals like to call them. Each pixel element works 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 ultimately 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 send the coloured light to 3 stand alone LCD panels. The 3 LCD panels form the elements of the image by shining 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 projected surface at the same time. The way a DLP projector operates is very different and even the produced image appears is not the same. With DLP, white light from the lamp is directed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image requires a sequence of red, blue and green light. The millions of micro mirrors as 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 eye will then draw each coloured element of the image into the single whole image. From LCD projectors, all colours are available all the time to create high brightness and great colour accuracy. In DLP, only one colour is available at a time, causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment in the colour wheel to improve brightness overall, but this also degrades colour accuracy.
I hear in forums all the time that DLP provides a higher contrast ratio and as such must be superior quality. For those 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 machine is able to produce. DLP projectors do have high contrast specifications compared to many LCD projectors. At one glance, this can seem to be an advantage, however, in the real world, the true black level is determined by the ambient light in the room in which the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you want to view needs moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most typical artifact that a DLP projector shows with moving images is colour break up. Colour break up is inherent in DLP systems because moving images keep changing between the time red, blue and green colours are shone. LCD projectors do not have this problem because every colour is sent simultaneously. DLP builders have developed 3DLP solutions using 3 chips to solve the colour break up error, but the cost of these projectors make them impractical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Take yourself back to high school science, and remember when they taught you how the different colours of light refract different amounts when shone through the same lens. The problem with DLP projectors is that they take the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously not the same and refract light at different levels. Most of the time with a DLP projector, a superfluous yellow colour will be projected above and some blue will come up below an image of something as simple as a straight black line. During manufacturing LCD projectors can be fixed to minimize these effects on the projected image, as each colour is processed on a separate LCD panels.
The only actual plus (excluding price) with taking a DLP projector is its smaller size and weight. However, this is only relevant to portability and has to be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is crucial to you, then the solution is easy. Take an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image blips. If you want to find out more about LCD technology in more detail, have a gander at this fantastic resource website: Explore 3LCD. If you have any additional questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online store 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.