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

The most typical 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, an acronym for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many business brands and models available, it can be overwhelming for consumers to make a decision between those technologies. The simple fact of the matter is that LCD projectors give superior image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with bringing up an equal level of image quality.

Visualise a set of blinds in your home over your bedroom window. By pulling on a rod you can turn the shutters open or closed, according to whether you want to let light in or not. Such is exactly how an LCD projector functions. Each pixel operates like its own 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 professionals like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from when the projector is turned on to when the picture reaches your screen is extremely significant in regard 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 project the coloured light to 3 individual LCD panels. The 3 LCD panels make the elements of the image by shining each pixel on and off. The pixels are then combined in a glass prism to form the projector image. Something important to understad about LCD projectors is that all three colours are directed onto your screen simultaneously. The way a DLP projector works is vastly different and even the final product of how an image appears 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 method of forming an image requires a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to create the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s vision will then pull together each coloured element of the image into a single full image. From LCD projectors, all colours are available all the time to offer the highest brightness and superb colour accuracy. In DLP, only one colour is available at any given time, and so causing lower colour brightness and accuracy. Some DLP designers have put a white segment into the colour wheel to improve general brightness, but this further degrades colour accuracy.

I hear in forums all the time that DLP provides a higher contrast ratio and ergo 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 system is capable of producing. DLP projectors do have high contrast specifications as compared to many LCD projectors. At a glance, this must be a plus, however, in reality, 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 needs moving images, DLP projection technology can also have 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 inherent in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this problem because all colours are projected at the same time. DLP builders have come up with 3DLP solutions using 3 chips to fix the colour break up artifacts, but the cost of these projectors make them not practical for many businesses and consumers.

Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and remember how various colours of light refract varied amounts when projected through the same lens. The problem 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 obviously different and refract light in different ways. Often with a DLP projector, some extra yellow colour will appear above and some blue will come through below something as simple as a single black line. In building LCD projectors can be fixed to minimize these effects on the projected image, as each colour is processed on isolated LCD panels.

The isolated true buy point (excluding price) with picking a DLP projector is its smaller total size and weight. However, this is only relevant for mobility and cannot be traded off against the image superiority of LCD projectors. If resulting picture quality is crucial to you, then the answer is a no-brainer. Go with an LCD projector! LCD projectors will always make bright, colourful images with fewer image blips. If you wish to know more about LCD technology in more detail, have a gander at 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 at Projector Central, Australia’s number one online retailer for projectors. Based in Brisbane, 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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