The typical question asked when looking for a new projector for the home, office, or classroom is: would I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many different brands and models available, it can be challenging for customers to choose between both technologies. The fact is that LCD projectors give superior image quality and colour accuracy. The next part of this article explains why DLP projectors struggle with bringing up a similar rate of image quality.
It’s like a set of blinds in your house over your bedroom window. With the twist of a rod you can have the shutters open or closed, depending on if you want to let light in or not. And such is exactly how an LCD projector behaves. Each pixel works like an individual shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as the pros like to call them. Each pixel element operates 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 picture reaches your screen is extremely significant 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 direct the coloured light to 3 individual LCD panels. The 3 LCD panels form the elements of the image by turning each pixel on and off. The pixels are then projected in a glass prism to create the projector image. A point to realise about LCD projectors is that all three colours are sent onto your projected surface all at once. The way a DLP projector runs is totally different and even how an image comes out is not the same. With DLP, white light from the lamp is sent through a turning 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 mentioned above reflect the coloured light on the pixels to produce the image elements. The elements of the image are cast 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 a complete image. Using LCD projectors, all colours are available all the time to offer the best brightness and great colour accuracy. In DLP, just one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some DLP manufacturers have put a white segment into the colour wheel to improve all over brightness, but this further degrades colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and ergo must be better 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 system is capable of producing. DLP projectors do have high contrast specifications when compared to a majority of LCD projectors. Initially, this can seem to be a benefit, however, in truth, the true black level is determined by the ambient light in the room while the projector is in use. Do not be fooled by contrast specifications on websites and in brochures.
When the content you wish to project includes moving images, DLP projection technology can also create image errors, or ‘artifacts’. The most typical artifact that a DLP projector shows with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this problem because all colours are delivered with the others. DLP manufacturers have developed 3DLP solutions using 3 chips to answer the colour break up error, but the price of these projectors make them hardly practical for most businesses and consumers.
Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Jump back to high school science, and recall how different colours of light refract varied amounts when passing through the same lens. The downfall with DLP projectors is that they take the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in a different way. Usually with a DLP projector, a spill of yellow colour will appear above and an extra blue will appear below an image containing something as simple as a straight black line. In manufacturing LCD projectors can be fixed to reduce these effects on the projected image, as each colour is projected on isolated LCD panels.
The one real plus (excluding price) with buying a DLP projector is its smaller total size and weight. However, this is only relevant with regard to transport and has to be traded off against the image advantages of LCD projectors. If the outcome of the picture quality is vital to you, then the answer is simple. Go with an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you want to learn more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any other questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one 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.