Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question that is asked when buying a new projector for the home, office, or classroom is: should I purchase an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and different models available, it can be overwhelming for customers to pick between both technologies. The simple fact of the matter is that LCD projectors have far better image quality and colour accuracy. The following article explains why DLP projectors struggle with reproducing a similar rate of image quality.
Imagine a set of blinds in your household covering your bedroom window. By pulling on a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector behaves. Each pixel functions like a unique shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element functions 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 extremely significant with regard to 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 create the elements of the image by switching each pixel on and off. The pixels are then projected in a glass prism to create the projector image. Something important to remember about LCD projectors is that all three colours are sent onto your wall all at the same time. The way a DLP projector functions is widely different and even the way an image looks 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 approach to 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 construct 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 draw each coloured element of the image into the single total image. In LCD projectors, all colours are available all the time to deliver the top level of brightness and spectacular colour accuracy. In DLP, only one colour is available at a time, and so causing lower colour brightness and accuracy. Some manufacturers have placed a white segment into the colour wheel to improve all over brightness, but this further lessens colour accuracy.
I see in forums all the time that DLP provides a higher contrast ratio and ergo 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 capable of producing. DLP projectors do provide high contrast specifications when compared to a majority of LCD projectors. At first glance, this can seem to be a plus, however, in reality, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you want to see requires moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most commonplace artifact that a DLP projector shows with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change up between the time red, blue and green colours are pulled up. LCD projectors do not have this characteristic because the colours are projected at once. DLP builders have created 3DLP solutions using 3 chips to solve the colour break up artifacts, but the price of these projectors make them almost impossible for the majority of businesses and consumers.
Another point of difference between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and remember how the different colours of light refract different amounts when passing through the same lens. The problem with DLP projectors is that they have the one same panel and the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light differently. Most of the time with a DLP projector, a superfluous yellow colour will show above and a spill of blue will show below an image as simple as a straight black line. In manufacturing LCD projectors can be adapted to take away these effects on the projected image, because each colour is directed on separate LCD panels.
The only actual benefit (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant to mobility 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 choice is a no-brainer. Take an LCD projector! LCD projectors will always produce bright, colourful images with fewer image mistakes. If you need to know more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any further questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s leading 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.
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