Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when purchasing a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, an acronym 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 different types available, it can be overwhelming for customers to choose between the two technologies. Ultimately LCD projectors give far better image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with reproducing a similar rate of image quality.
It’s like a set of blinds in your household over your bedroom window. With the twist of a rod you can make the shutters open or closed, according to if you want to let light in or not. And that is exactly how an LCD projector functions. Each pixel works like a unique 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 pros like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point when the projector is turned on to when the image reaches your screen is absolutely significant in regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to form the projector image. Something to understad about LCD projectors is that all three colours are projected onto your projected surface simultaneously. The way a DLP projector functions is totally different and even the way an image appears is not the same. With DLP, white light from the lamp is processed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of making 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 cast 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 total image. Using LCD projectors, all colours are available all the time to offer the best brightness and fantastic colour accuracy. In DLP, only one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some manufacturers have included a white segment into the colour wheel to improve brightness generally, but this then detracts from colour accuracy.
I find in forums all the time that DLP provides a higher contrast ratio and therefore must be superior. 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 projector is capable of. DLP projectors do offer high contrast specifications as compared to a majority of LCD projectors. At first glance, this can seem to be a benefit, however, in truth, the true black level is determined by the ambient light in the room where the projector is in use. Do not be duped by contrast specifications on websites and in brochures.
When the content you want to see requires moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because all colours are processed at once. DLP developers have created 3DLP solutions using 3 chips to solve the colour break up issue, but the expense of these projectors make them hardly practical for the large part of businesses and consumers.
Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and recall when they taught you how various colours of light refract varied amounts when directed 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, a spill of yellow colour will appear above and a spill of blue will show below something as simple as a single black line. In manufacturing LCD projectors can be adjusted to remove these effects on the projected image, as each colour is refracted on separate LCD panels.
The sole true plus (excluding price) with going with a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to transport and needs to be traded off against the image superiority of LCD projectors. If resulting picture quality is crucial to you, then the answer is simple. Choose an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image errors. If you need to learn more about LCD technology in more detail, have a look at this fantastic resource website: Explore 3LCD. If you have any other 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 store for projectors. Brisbane based, 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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