Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question that is asked when purchasing a new projector for the home, office, or classroom is: should I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and models available, it can be confusing for customers to pick between these technologies. Ultimately LCD projectors offer far superior image quality and colour accuracy. The next paragraph tells you why DLP projectors struggle with projecting a similar 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, according to if you want to let light in or not. And such is exactly how an LCD projector works. 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 constructed of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element operates 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 picture reaches your screen is ultimately important with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 different LCD panels. The 3 LCD panels form the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to deliver the projector image. A point to know about LCD projectors is that all three colours are sent onto your projected surface all at once. The way a DLP projector functions is vastly different and even the produced image appears is not the same. With DLP, white light from the lamp is directed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of creating 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 displayed in sequence on the screen, one colour at a time. The viewer’s eyes will then pull together each coloured element of the image into a single full image. With LCD projectors, all colours are available all the time to form the best brightness and great colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some manufacturers have put a white segment into the colour wheel to improve overall brightness, but this also damages colour accuracy.
I read in forums all the time that DLP gives a higher contrast ratio and thus must be better. For those who are 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 projector is capable of. DLP projectors do offer high contrast specifications as compared to many LCD projectors. Initially, this must be a benefit, however, in the real world, the true black level is determined by the ambient light in the room in which the projector is used. Do not be tricked by contrast specifications on websites and in brochures.
When the content you plan to see requires moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this downside because all the colours are delivered with the others. DLP developers have formed 3DLP solutions using 3 chips to fix the colour break up error, but the cost of these projectors make them hardly practical for the large part of businesses and consumers.
Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and they taught you how various colours of light refract different amounts when directed through the same lens. The downfall with DLP projectors is that they use 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. Usually with a DLP projector, an extra yellow colour will show above and a superfluous blue will be projected below an image as simple as a lone black line. In building LCD projectors can be adjusted to remove these effects on the projected image, because each colour is projected on its own LCD panels.
The only true plus (excluding price) with picking a DLP projector is its 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 important to you, then the answer is simple. Go with an LCD projector! LCD projectors will always make bright, colourful images with fewer image blips. If you wish to ask more about LCD technology in more detail, see this spectacular 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 at Projector Central, Australia’s top online store 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.
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