Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question that is asked when buying a new projector for the home, office, or classroom is: would I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and different models available, it can be challenging for customers to choose between both technologies. The fact is that LCD projectors provide better image quality and colour accuracy. The following article will tell you why DLP projectors struggle with reproducing an equal standard of image quality.
Imagine a set of blinds in your room for your bedroom window. With the twist of a rod you can have the shutters open or closed, according to if you want to let light in or not. Such is exactly how an LCD projector works. Each pixel operates like a unique shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the point at which the projector is turned on to when the picture reaches your screen is ultimately significant 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 shining each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. A point to know about LCD projectors is that all three colours are projected onto your projected surface all at the same time. The way a DLP projector runs is vastly different and even how 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 way of forming an image forms a sequence of red, blue and green light. The millions of micro mirrors as described 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 eye will then combine each coloured element of the image into a single whole image. In LCD projectors, all colours are available all the time to offer the top level of brightness and fantastic colour accuracy. In DLP, just one colour is available at once, and so causing lower colour brightness and accuracy. Some developers have included a white segment for the colour wheel to improve all over brightness, but this goes and degrades colour accuracy.
I find in forums all the time that DLP gives a higher contrast ratio and therefore must be better quality. 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 system is able to produce. DLP projectors do offer high contrast specifications as compared to a majority of LCD projectors. At a glance, this can seem to be an advantage, however, in truth, the true black level is determined by the ambient light in the room where the projector is used. Do not be duped by contrast specifications on websites and in brochures.
When the content you wish to see includes moving images, DLP projection technology also has image errors, or ‘artifacts’. The most common artifact that a DLP projector displays with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images keep changing between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because all colours are sent at the same time. DLP developers have come up with 3DLP solutions using 3 chips to fix the colour break up artifacts, but the cost of these projectors make them impractical for most businesses and consumers.
Another point of difference between LCD and DLP is how they compensate for the refractive qualities of light. Take yourself back to high school science, and remember how various colours of light refract different amounts when directed through the same lens. The downside with DLP projectors is that they have the one same panel and the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Usually with a DLP projector, some yellow colour will come up above and a spill of blue will be projected below an image containing something as simple as a lone black line. While being built LCD projectors can be adapted to reduce these effects on the projected image, because each colour is directed on separate LCD panels.
The only actual advantage (excluding price) with buying a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to transporting the device and must be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is vital to you, then the choice is easy. Take an LCD projector! LCD projectors will constantly produce bright, colourful images with fewer image mistakes. If you wish to ask more about LCD technology in more detail, see this fabulous resource website: Explore 3LCD. If you have any persisting questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s premier online retailer for projectors. Based in Brisbane, Projector Central has served Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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