Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question heard when looking for a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and different models available, it can be overwhelming for the buyer 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 article below explains why DLP projectors struggle with reproducing a comparable grade of image quality.
Think of a set of blinds in your room covering your bedroom window. By pulling on a rod you can make the shutters open or closed, depending on if you want to let light in or not. Such is exactly how an LCD projector functions. Each pixel works like an individual shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is constructed 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 when the projector turns on to when the image reaches your screen is extremely important in regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by separating it into red, blue and green components, by three mirrors which send the coloured light to 3 stand alone LCD panels. The 3 LCD panels create the elements of the image by shining each pixel on and off. The pixels are then projected in a glass prism to create the projector image. Something to know about LCD projectors is that all three colours are sent onto your projected surface all at the same time. The way a DLP projector functions is totally different and even the way an image looks 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 way of making an image casts a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to form the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into the single whole image. From LCD projectors, all colours are available all the time to offer the top level of brightness and superb colour accuracy. In DLP, only one colour is available at a time, and so resulting in lower colour brightness and accuracy. Some designers have placed a white segment into the colour wheel to improve brightness overall, but this further degrades colour accuracy.
I see in forums all the time that DLP gives a higher contrast ratio and thus must be superior. For those who do not 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 system is capable of producing. DLP projectors do offer high contrast specifications when compared to many LCD projectors. At first glance, this appears to be a benefit, however, in real life, the true black level is determined by the ambient light in the room while the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to view includes moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most common 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 pulled up. LCD projectors do not have this problem because the colours are processed at the same time. DLP manufacturers have created 3DLP solutions using 3 chips to resolve the colour break up error, but the price tag of these projectors make them almost impossible for the majority of businesses and consumers.
Another differentiation between LCD and DLP is how they match the balance for the refractive qualities of light. Remember back to high school science, and recall how different colours of light refract different amounts when passing through the same lens. The problem with DLP projectors is that they utilise the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in different ways. Most of the time with a DLP projector, some extra yellow colour will be projected above and some extra blue will appear below an image containing something as simple as a single black line. In manufacturing LCD projectors can be set to remove these effects on the projected image, because each colour is directed on a separate LCD panels.
The only real plus (excluding price) with picking a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to mobility and cannot 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 no-brainer. Go for an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image mistakes. If you wish to find out more about LCD technology in more detail, check out this tremendous resource website: Explore 3LCD. If you have any persisting questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s premier online shop for projectors. Brisbane based, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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