Projectors: LCD Verses DLP (The downfall of DLP technology)

The common question heard when looking for a new projector for the home, office, or classroom is: would I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and types available, it can be confusing for consumers to choose between both technologies. The simple fact of the matter is that LCD projectors have far superior image quality and colour accuracy. The next paragraph explains why DLP projectors struggle with creating a similar standard of image quality.

Imagine 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 functions. 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 constructed 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 the time the projector is turned on to when the picture reaches your screen is vitally important to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by dividing it into red, blue and green components, by three mirrors which transfer the coloured light to 3 different LCD panels. The 3 LCD panels create the elements of the image by switching each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. A significant point to remember about LCD projectors is that all three colours are directed onto your screen at once. The way a DLP projector operates is totally different and even the produced image shows up is not the same. With DLP, white light from the lamp is processed through a turning 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 as mentioned above reflect the coloured light on the pixels to create 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 total image. In LCD projectors, all colours are available all the time to deliver high brightness and great colour accuracy. In DLP, only one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP designers have placed a white segment in the colour wheel to improve brightness overall, but this goes and detracts from colour accuracy.

I hear in forums all the time that DLP has a higher contrast ratio and thus must be better. 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 technology is capable of. DLP projectors do provide high contrast specifications when compared to many LCD projectors. At a glance, this must be an advantage, 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 plan to view needs moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most often seen artifact that a DLP projector displays 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 displayed. LCD projectors do not have this characteristic because all the colours are delivered at the same time. DLP designers have come up with 3DLP solutions using 3 chips to fix the colour break up artifacts, but the expense of these projectors make them almost impossible for most businesses and consumers.

Another differentiation between LCD and DLP is how they compensate for the refractive qualities of light. Take yourself back to high school science, and remember when they taught you how the various colours of light refract different amounts when projected through the same lens. The downfall with DLP projectors is that they take the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in a different way. Most of the time with a DLP projector, some yellow colour will appear above and a spill of blue will come up below an image of something as simple as a straight black line. In building LCD projectors can be fixed to minimize these effects on the projected image, because each colour is directed on a 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 to transport and needs to be traded off against the image superiority of LCD projectors. If resulting picture quality is vital to you, then the answer is no-brainer. Choose an LCD projector! LCD projectors will consistently make bright, colourful images with fewer image blips. If you want to learn more about LCD technology in more detail, check out this tremendous 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 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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