Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question asked when buying a new projector for the home, office, or classroom is: should I buy an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and types available, it can be challenging for consumers to choose between the two technologies. It comes down to the fact that LCD projectors offer far superior image quality and colour accuracy. The next part of this article tells you why DLP projectors struggle with bringing up a similar standard of image quality.
It’s like a set of blinds in your home over your bedroom window. With the twist of a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And such is exactly how an LCD projector operates. Each pixel works 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 experts like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the time the projector turns on to when the image reaches your screen is absolutely important 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 direct the coloured light to 3 stand alone 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 create the projector image. An important point to remember about LCD projectors is that all three colours are delivered onto your wall all at once. The way a DLP projector works is widely different and even the produced 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 forming an image requires a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to produce 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 the single whole image. Using LCD projectors, all colours are available all the time to deliver high brightness and great colour accuracy. In DLP, just one colour is available at once, and so causing lower colour brightness and accuracy. Some developers have put a white segment for the colour wheel to improve all over brightness, but this goes and damages colour accuracy.
I read in forums all the time that DLP provides a higher contrast ratio and ergo must be superior. 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 system is capable of producing. DLP projectors do provide high contrast specifications as compared to most LCD projectors. At first glance, this can seem to be a plus, however, in reality, 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 wish to bring to life includes 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 inherent in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this problem because all the colours are delivered at the same time. DLP builders have developed 3DLP solutions using 3 chips to resolve the colour break up error, but the price of these projectors make them hardly practical for most businesses and consumers.
Another differentiation between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and recall when they taught you how the different colours of light refract varied amounts when passing through the same lens. The downfall 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 obviously not the same and refract light at different levels. Most of the time with a DLP projector, some yellow colour will come through above and an extra blue will come up below an image containing something as simple as a single black line. In manufacturing LCD projectors can be set to minimize these effects on the projected image, because each colour is refracted on a separate LCD panels.
The one veritable plus (excluding price) with going with a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to mobility and cannot be traded off against the image plusses of LCD projectors. If the result of the picture quality is vital to you, then the decision is a no-brainer. Choose an LCD projector! LCD projectors will always make bright, colourful images with fewer image mistakes. If you wish to know more about LCD technology in more detail, have a look at this fabulous resource website: Explore 3LCD. If you have any further questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s premier online retailer for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
