Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question customers ask when acquiring a new projector for the home, office, or classroom is: would I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and different models available, it can be overwhelming for customers to choose between those technologies. Ultimately LCD projectors provide superior image quality and colour accuracy. The next paragraph explains why DLP projectors struggle with bringing up an equal standard of image quality.
Think of a set of blinds in your house over your bedroom window. By pulling a rod you can turn the shutters open or closed, according to if you want to let light in or not. And such is exactly how an LCD projector operates. Each pixel works like a single shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the point when the projector turns on to when the picture reaches your screen is vitally significant to image quality, brightness and colour accuracy. LCD projectors project 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 create the elements of the image by shining each pixel on and off. The pixels are then projected in a glass prism to send the projector image. A point to know about LCD projectors is that all three colours are delivered onto your projected surface 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 projected 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 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 eye will then combine each coloured element of the image into a single full image. From LCD projectors, all colours are available all the time to form the highest brightness and superb colour accuracy. In DLP, just one colour is available at a time, and so resulting in lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment into the colour wheel to improve overall brightness, but this also degrades colour accuracy.
I see in forums all the time that DLP offers a higher contrast ratio and as such must be superior quality. For those who are unsure, 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 have high contrast specifications compared to most LCD projectors. At a glance, this can seem to be an advantage, however, in truth, the true black level is determined by the ambient light in the room when the projector is being utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to bring to life needs moving images, DLP projection technology also has image marks, or ‘artifacts’. The most common 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 pulled up. LCD projectors do not have this disadvantage because every colour is projected with the others. DLP designers have come up with 3DLP solutions using 3 chips to resolve the colour break up issue, but the expense of these projectors make them almost impossible for many businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Remember back to high school science, and remember when they taught you how the different colours of light refract differing amounts when projected through the same lens. The downfall with DLP projectors is that they utilise the one same panel with the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light in a different way. Often with a DLP projector, some extra yellow colour will show above and some extra blue will come up below something as simple as a single black line. In building LCD projectors can be adapted to take away these effects on the projected image, as each colour is processed on isolated LCD panels.
The one real buy point (excluding price) with going with a DLP projector is its smaller overall size and weight. However, this is only relevant for mobility and needs to be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is vital to you, then the solution is no-brainer. Take an LCD projector! LCD projectors will consistently produce bright, colourful images with fewer image mistakes. If you desire to know more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s leading online shop for projectors. Based in Brisbane, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
