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

The most typical question heard when buying a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most popular projector imaging technologies. With so many company brands and different models available, it can be confusing for consumers to choose between those technologies. The fact is that LCD projectors give far superior image quality and colour accuracy. The following article will explain why DLP projectors struggle with creating the same rate of image quality.

It’s like a set of blinds in your home covering your bedroom window. By pulling on a rod you can have the shutters open or closed, according to if you want to let light in or not. That is exactly how an LCD projector works. Each pixel functions like a single shutter on a set of blinds to either send light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element operates to either reflect light or block it.

How the light source is processed from the time the projector is switched on to when the content reaches your screen is ultimately significant for image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting 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 processing each pixel on and off. The pixels are then combined in a glass prism to deliver the projector image. A point to understad about LCD projectors is that all three colours are sent onto your projected surface all at the same time. The way a DLP projector operates is very 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 creating an image requires a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to produce 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 combine each coloured element of the image into the full image. Using LCD projectors, all colours are available all the time to offer the best brightness and great colour accuracy. In DLP, only one colour is available at once, resulting in lower colour brightness and accuracy. Some DLP designers have put a white segment into the colour wheel to improve brightness generally, but this also degrades colour accuracy.

I see in forums all the time that DLP gives a higher contrast ratio and ergo must be superior quality. For those who are 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 machine is able to produce. DLP projectors do offer high contrast specifications when compared to the majority of LCD projectors. At first 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 being utilised. Do not be fooled by contrast specifications on websites and in brochures.

When the content you are trying to bring to life requires moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most common artifact that a DLP projector forms 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 pulled up. LCD projectors do not have this downside because all colours are sent simultaneously. DLP designers have developed 3DLP solutions using 3 chips to resolve the colour break up problem, but the price of these projectors make them almost impossible for the large part of businesses and consumers.

Another variance between LCD and DLP is how they match the balance for the refractive qualities of light. Remember back to high school science, and remember how various colours of light refract different amounts when passing through the same lens. The disadvantage 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 a different way. Usually with a DLP projector, a spill of yellow colour will come up above and an extra blue will appear below an image containing 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 processed on separate LCD panels.

The only actual buy point (excluding price) with deciding on a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to mobility and cannot be traded off against the image benefits of LCD projectors. If overall picture quality is crucial to you, then the solution is a no-brainer. Go for an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image blips. If you desire to learn more about LCD technology in more detail, have a gander at this fantastic resource website: Explore 3LCD. If you have any other questions, jump onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager at Projector Central, Australia’s leading online retailer for projectors. Based in Brisbane, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.