The typical question asked when looking for a new projector for the home, office, or classroom is: will I get 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 company brands and different models available, it can be challenging for clients to decide between these technologies. Ultimately LCD projectors offer better image quality and colour accuracy. The next part of this article tells you why DLP projectors struggle with projecting a comparable rate of image quality.
Think of a set of blinds in your home over your bedroom window. By pulling 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 works. Each pixel operates like an individual shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the time the projector switches on to when the picture reaches your screen is vitally significant for image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which direct the coloured light to 3 different LCD panels. The 3 LCD panels form the elements of the image by shining each pixel on and off. The pixels are then combined in a glass prism to form the projector image. Something important to know about LCD projectors is that all three colours are directed onto your projector screen all at the same time. The way a DLP projector runs is widely different and even the produced image shows up 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 forms a sequence of red, blue and green light. The millions of micro mirrors mentioned 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 vision will then put together each coloured element of the image into the total image. From LCD projectors, all colours are available all the time to form the top level of brightness and superb colour accuracy. In DLP, just one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP designers have placed a white segment into the colour wheel to improve all over brightness, but this further damages colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and as such 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 technology is capable of producing. DLP projectors do provide high contrast specifications as compared to most LCD projectors. Initially, this can seem to be an advantage, however, in the real world, the true black level is determined by the ambient light in the room when the projector is being utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you want to see has moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change position between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because all the colours are sent at the same time. DLP builders have come up with 3DLP solutions using 3 chips to answer the colour break up artifacts, but the expense of these projectors make them almost impossible for most businesses and consumers.
Another differentiation between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and remember when they taught you how the various colours of light refract differing amounts when projected through the same lens. The downside with DLP projectors is that they have the one same panel with the same lens to project Red, Blue and Green. All 3 colours are different and refract light in a different way. Generally with a DLP projector, a superfluous yellow colour will appear above and some blue will be projected below an image containing something as simple as a straight black line. While being built LCD projectors can be set to take away these effects on the projected image, as each colour is directed on isolated LCD panels.
The one veritable plus (excluding price) with picking a DLP projector is its overall smaller size and weight. However, this is only relevant for portability and must be traded off against the image superiority of LCD projectors. If resulting picture quality is vital to you, then the solution is simple. Go with an LCD projector! LCD projectors will consistently produce bright, colourful images with fewer image blips. If you want to ask more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any persisting questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online retailer for projectors. Based in Brisbane, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.