Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question asked when looking for a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, standing 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 challenging for consumers to decide between both technologies. It comes down to the fact that LCD projectors have better image quality and colour accuracy. The article below will explain why DLP projectors struggle with bringing up the same rate of image quality.
Imagine a set of blinds in your house for 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. This is exactly how an LCD projector works. Each pixel functions like an individual shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as professionals 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 is turned on to when the image reaches your screen is absolutely significant to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 stand alone 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 send the projector image. Something important to realise about LCD projectors is that all three colours are delivered onto your projected surface at the same time. The way a DLP projector works is very different and even the final product of how an image comes out 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 approach to creating an image creates a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to form 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 combine 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 fantastic colour accuracy. In DLP, just one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment for the colour wheel to improve overall brightness, but this further degrades colour accuracy.
I find in forums all the time that DLP gives a higher contrast ratio and ergo must be better. For those who don’t 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 technology is capable of producing. DLP projectors do possess high contrast specifications compared to many LCD projectors. At first glance, this seems to be an advantage, however, in the real world, the true black level is determined by the ambient light in the room where the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you are trying to bring to life needs moving images, DLP projection technology can also create image errors, or ‘artifacts’. The most common 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 between the time red, blue and green colours are displayed. LCD projectors do not have this downside because all the colours are projected with the others. DLP developers have come up with 3DLP solutions using 3 chips to answer the colour break up error, but the price of these projectors make them impractical for the majority of businesses and consumers.
Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Remember back to high school science, and they taught you how the various colours of light refract differing amounts when directed through the same lens. The disadvantage 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. Usually with a DLP projector, a spill of yellow colour will come through above and a superfluous blue will come up below an image as simple as a lone black line. During manufacturing LCD projectors can be adjusted to reduce these effects on the projected image, because each colour is processed on a separate LCD panels.
The sole veritable advantage (excluding price) with going with a DLP projector is its overall smaller size and weight. However, this is only relevant to transporting the device and must be traded off against the image plusses of LCD projectors. If the result of the picture quality is important to you, then the answer is a no-brainer. Take an LCD projector! LCD projectors will definitely create bright, colourful images with fewer image imperfections. If you wish to ask more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any additional questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s premier online shop for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
