Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical 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, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and different types available, it can be overwhelming for clients to make a choice between those technologies. The simple fact of the matter is that LCD projectors provide superior image quality and colour accuracy. The article below tells you why DLP projectors struggle with bringing up the same level of image quality.
It’s like a set of blinds in your room over your bedroom window. By pulling a rod you can turn the shutters open or closed, according to whether you want to let light in or not. That is exactly how an LCD projector works. Each pixel functions like its own shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the time the projector is turned on to when the content reaches your screen is extremely significant to image quality, brightness and colour accuracy. LCD projectors process 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 cast the elements of the image by shining each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. An important point to realise about LCD projectors is that all three colours are projected onto your projector screen simultaneously. The way a DLP projector functions is totally different and even the final product of how an image appears is not the same. With DLP, white light from the lamp is projected through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of creating an image requires 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 vision will then put together each coloured element of the image into a total image. With LCD projectors, all colours are available all the time to offer the highest brightness and great colour accuracy. In DLP, just one colour is available at a time, resulting in lower colour brightness and accuracy. Some developers have added a white segment in the colour wheel to improve overall brightness, but this further detracts from colour accuracy.
I find in forums all the time that DLP gives a higher contrast ratio and ergo must be superior. For those who don’t know, 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 able to produce. DLP projectors do offer high contrast specifications compared to many LCD projectors. At one glance, this seems to be a benefit, however, in reality, the true black level is determined by the ambient light in the room when the projector is in use. Do not be duped by contrast specifications on websites and in brochures.
When the content you want to see needs moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is inherent 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 colours are delivered simultaneously. DLP designers have formed 3DLP solutions using 3 chips to resolve the colour break up problem, but the price tag of these projectors make them impractical for most businesses and consumers.
Another difference between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and remember how the various colours of light refract differing amounts when passing through the same lens. The disadvantage with DLP projectors is that they have 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 in a different way. Often with a DLP projector, some yellow colour will be projected above and a spill of blue will show below an image as simple as a single black line. In building LCD projectors can be adapted to remove these effects on the projected image, as each colour is directed on separate LCD panels.
The sole actual buy point (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant for portability and must be traded off against the image advantages of LCD projectors. If the outcome of the picture quality is important to you, then the answer is simple. Choose an LCD projector! LCD projectors will always produce bright, colourful images with fewer image imperfections. If you desire to know more about LCD technology in more detail, see this fabulous resource website: Explore 3LCD. If you have any other questions, get onto 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. Brisbane-based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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