Mining Wise International

The most common question that is asked when purchasing a new projector for the home, office, or classroom is: would I take an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many company brands and models available, it can be overwhelming for the buyer to make a decision between these technologies. It comes down to the fact that LCD projectors have better image quality and colour accuracy. The following article will explain why DLP projectors struggle with projecting an equal standard of image quality.

Think of a set of blinds in your household over your bedroom window. With the twist of a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And this is exactly how an LCD projector works. Each pixel operates like a unique shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element works to either reflect light or block it.

How the light source is processed from when the projector switches on to when the content reaches your screen is vitally important for image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by separating it into red, blue and green components, by three mirrors which project the coloured light to 3 different LCD panels. The 3 LCD panels form the elements of the image by switching each pixel on and off. The pixels are then meshed in a glass prism to create the projector image. A point to realise about LCD projectors is that all three colours are projected onto your wall at the same time. The way a DLP projector works is totally 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 forming an image casts a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to create the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s vision will then draw each coloured element of the image into the single complete image. Using LCD projectors, all colours are available all the time to offer the top level of brightness and fantastic colour accuracy. In DLP, only one colour is available at a time, and so causing lower colour brightness and accuracy. Some designers have added a white segment in the colour wheel to improve overall brightness, but this further degrades colour accuracy.

I read in forums all the time that DLP gives a higher contrast ratio and as such must be superior quality. 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 machine is able to produce. DLP projectors do provide high contrast specifications in comparison to many LCD projectors. At one glance, this must be a plus, however, in truth, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be hoodwinked 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 create image marks, or ‘artifacts’. The most commonplace artifact that a DLP projector displays 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 problem because all the colours are processed with the others. DLP developers have created 3DLP solutions using 3 chips to answer the colour break up problem, but the cost of these projectors make them impractical for the majority of businesses and consumers.

Another variance between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and remember when they taught you how the different colours of light refract differing amounts when shone through the same lens. The disadvantage with DLP projectors is that they take the one same panel for the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light differently. Generally with a DLP projector, a spill of yellow colour will appear above and a spill of blue will come through below an image of something as simple as a lone black line. While being built LCD projectors can be adjusted to remove these effects on the projected image, because each colour is projected on a separate LCD panels.

The only veritable plus (excluding price) with buying a DLP projector is its smaller size and weight. However, this is only relevant in regard to portability and cannot be traded off against the image superiority of LCD projectors. If the result of the picture quality is important to you, then the answer is simple. Go for an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you wish to find out more about LCD technology in more detail, see 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 of Projector Central, Australia’s top online retailer for projectors. Brisbane-based, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.