The most typical question asked when looking for a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many company brands and models available, it can be confusing for customers to make a decision between those technologies. The simple fact of the matter is that LCD projectors have superior image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with bringing up an equal rate of image quality.
Think of a set of blinds in your home for your bedroom window. By pulling a rod you can make 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 its own shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is formed 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 when the projector turns on to when the picture reaches your screen is extremely significant in regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 separate 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 delivered onto your screen simultaneously. The way a DLP projector functions is widely different and even the produced 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 way of forming an image forms 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 sent in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into a total image. From LCD projectors, all colours are available all the time to deliver the top level of brightness and spectacular colour accuracy. In DLP, just one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some DLP designers have put a white segment for the colour wheel to improve all over brightness, but this also degrades colour accuracy.
I find in forums all the time that DLP has a higher contrast ratio and ergo 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 projector is capable of. DLP projectors do have high contrast specifications compared to most LCD projectors. At first glance, this can seem to be a benefit, however, in the real world, the true black level is determined by the ambient light in the room where the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to project includes moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most often seen 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 downside because all colours are sent simultaneously. DLP builders have created 3DLP solutions using 3 chips to answer the colour break up problem, but the expense of these projectors make them impractical for most businesses and consumers.
Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Remember back to high school science, and remember 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 with the same lens to project Red, Blue and Green. All 3 colours are obviously different 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 of something as simple as a lone black line. In building LCD projectors can be adapted to minimize these effects on the projected image, because each colour is projected on a separate LCD panels.
The only actual plus (excluding price) with deciding on a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to mobility and has to be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is important to you, then the solution is simple. Take an LCD projector! LCD projectors will always produce bright, colourful images with fewer image imperfections. If you want to know more about LCD technology in more detail, check out this fantastic 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 of Projector Central, Australia’s top online provider for projectors. Based in Brisbane, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
Tags: data projectors brisbane, data projectors gold coastJuly 19th, 2010UncategorizedRead More >No Comments