Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question that is asked when looking for a new projector for the home, office, or classroom is: do I get 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 most common projector imaging technologies. With so many different brands and types available, it can be difficult for customers to pick between these technologies. The simple fact of the matter is that LCD projectors provide superior image quality and colour accuracy. The next part of this article tells you why DLP projectors struggle with creating the same grade of image quality.
It’s like a set of blinds in your household over your bedroom window. By twisting a rod you can make the shutters open or closed, according to whether you want to let light in or not. This is exactly how an LCD projector functions. Each pixel operates like a single shutter on a set of blinds to either send light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point when the projector switches on to when the image reaches your screen is vitally important to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by cutting it into red, blue and green components, by three mirrors which direct the coloured light to 3 separate LCD panels. The 3 LCD panels create the elements of the image by shining each pixel on and off. The pixels are then meshed in a glass prism to send the projector image. Something important to understad about LCD projectors is that all three colours are projected onto your projector screen all at the same time. The way a DLP projector runs is vastly different and even how an image comes out is not the same. With DLP, white light from the lamp is projected 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 construct the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eye will then pull together each coloured element of the image into the whole image. With LCD projectors, all colours are available all the time to deliver the top level of brightness and great colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some designers have added a white segment into the colour wheel to improve brightness overall, but this then lessens colour accuracy.
I see in forums all the time that DLP gives a higher contrast ratio and therefore must be better quality. For those who do not know, 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 able to produce. DLP projectors do possess high contrast specifications when compared to a majority of LCD projectors. At a glance, this must be a benefit, however, in the real world, the true black level is determined by the ambient light in the room when the projector is in use. Do not be duped by contrast specifications on websites and in brochures.
When the content you are trying to bring to life includes moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images keep changing between the time red, blue and green colours are projected. LCD projectors do not have this disadvantage because all colours are processed at the same time. DLP manufacturers have come up with 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the price of these projectors make them almost impossible for the majority of businesses and consumers.
Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Take yourself back to high school science, and recall how various colours of light refract varied amounts when projected through the same lens. The problem with DLP projectors is that they use the one same panel for the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light in a different way. Generally with a DLP projector, some yellow colour will come up above and a superfluous blue will show below an image of something as simple as a single black line. While being built LCD projectors can be adapted to minimize these effects on the projected image, because each colour is processed on separate LCD panels.
The sole veritable buy point (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant to transporting the device and has to be traded off against the image plusses of LCD projectors. If overall picture quality is vital to you, then the answer is simple. Go for an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image blips. If you need to learn more about LCD technology in more detail, have a gander at this spectacular 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 for Projector Central, Australia’s top online store for projectors. Brisbane-based, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.