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

The most common question that is asked when purchasing a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, short 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 different models available, it can be overwhelming for customers to choose between these technologies. The fact is that LCD projectors give better image quality and colour accuracy. The article below tells you why DLP projectors struggle with bringing up the same rate of image quality.

Think of a set of blinds in your household for your bedroom window. By pulling 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 works like a unique shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as professionals 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 content reaches your screen is extremely significant to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by dividing 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 cast the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to create the projector image. An important point to realise about LCD projectors is that all three colours are delivered onto your screen at the same time. The way a DLP projector runs is vastly different and even the final product of how an image comes out is not the same. With DLP, white light from the lamp is sent through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of making an image creates a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to form 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. In LCD projectors, all colours are available all the time to form top brightness and great colour accuracy. In DLP, only one colour is available at any given time, and so causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment in the colour wheel to improve brightness overall, but this further lessens colour accuracy.

I see in forums all the time that DLP has a higher contrast ratio and thus must be superior quality. 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 technology is able to produce. DLP projectors do possess high contrast specifications in comparison to the majority of LCD projectors. At first glance, this seems to be an advantage, however, in reality, the true black level is determined by the ambient light in the room while the projector is used. Do not be tricked by contrast specifications on websites and in brochures.

When the content you plan to see has moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most often seen artifact that a DLP projector displays with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change position between the time red, blue and green colours are shone. LCD projectors do not have this problem because all colours are delivered at the same time. DLP builders have come up with 3DLP solutions using 3 chips to answer the colour break up issue, but the cost of these projectors make them not practical for the large part of businesses and consumers.

Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and recall when they taught you how the various colours of light refract varied amounts when directed through the same lens. The downside with DLP projectors is that they have the one same panel for the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light differently. Generally with a DLP projector, some yellow colour will come through above and a spill of blue will show below an image as simple as a lone black line. While being built LCD projectors can be adapted to minimize these effects on the projected image, as each colour is processed on isolated LCD panels.

The sole actual benefit (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant with regard to portability and cannot be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is crucial to you, then the solution is simple. Take an LCD projector! LCD projectors will definitely produce bright, colourful images with fewer image errors. If you desire to ask more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any persisting questions, get onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager with Projector Central, Australia’s leading 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.