Projectors: LCD Verses DLP (The downfall of DLP technology)
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The typical question asked when looking for a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and types available, it can be confusing for clients to make a choice between the two technologies. Ultimately LCD projectors have better image quality and colour accuracy. The following article tells you why DLP projectors struggle with bringing up a similar grade of image quality.
Visualise a set of blinds in your room covering your bedroom window. By twisting a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. This is exactly how an LCD projector operates. Each pixel functions like a single shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from when the projector switches on to when the image reaches your screen is absolutely important to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by separating it into red, blue and green components, by three mirrors which project the coloured light to 3 stand alone LCD panels. The 3 LCD panels cast the elements of the image by switching each pixel on and off. The pixels are then simultaneously processed in a glass prism to create the projector image. An important point to remember about LCD projectors is that all three colours are delivered onto your projected surface all at the same time. The way a DLP projector runs is vastly different and even the produced image shows up 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 projecting an image creates 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 cast 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. Using LCD projectors, all colours are available all the time to create high brightness and superb colour accuracy. In DLP, just one colour is available at any given time, and so causing lower colour brightness and accuracy. Some developers have added a white segment into the colour wheel to improve all over brightness, but this further damages colour accuracy.
I find in forums all the time that DLP provides a higher contrast ratio and ergo must be superior quality. For those uncertain, 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 provide high contrast specifications when compared to most LCD projectors. At a glance, this appears to be a plus, however, in truth, the true black level is determined by the ambient light in the room when the projector is being utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you want to bring to life includes moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector creates with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change position between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because every colour is delivered with the others. DLP manufacturers have created 3DLP solutions using 3 chips to fix the colour break up error, but the cost of these projectors make them hardly practical for most businesses and consumers.
Another point of difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and recall how various colours of light refract different amounts when shone 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 different and refract light in a different way. Most of the time with a DLP projector, a superfluous yellow colour will come up above and some extra blue will come through below an image containing something as simple as a lone black line. In building LCD projectors can be set to take away these effects on the projected image, as each colour is directed on separate LCD panels.
The isolated veritable benefit (excluding price) with picking a DLP projector is its smaller size and weight. However, this is only relevant with regard to transporting the device and has to be traded off against the image advantages of LCD projectors. If the outcome of the picture quality is vital to you, then the solution is easy. Go for an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you desire to find out more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any additional questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s number one online shop for projectors. Brisbane based, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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