Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when acquiring a new projector for the home, office, or classroom is: should I purchase an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, short 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 the buyer to pick between these technologies. It comes down to the fact that LCD projectors provide better image quality and colour accuracy. The next paragraph will tell you why DLP projectors struggle with reproducing an equal grade of image quality.
Think of a set of blinds in your household on your bedroom window. By pulling on a rod you can have the shutters open or closed, according to if you want to let light in or not. Such is exactly how an LCD projector behaves. Each pixel functions like an individual shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is formed 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 when the projector is turned on to when the content reaches your screen is extremely important for image quality, brightness and colour accuracy. LCD projectors shine 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 deliver the projector image. Something to realise about LCD projectors is that all three colours are directed onto your projector screen at the same time. The way a DLP projector works is very different and even the final product of how an image appears is not the same. With DLP, white light from the lamp is directed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of creating 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 cast 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 complete image. From LCD projectors, all colours are available all the time to offer the highest brightness and fantastic colour accuracy. In DLP, just one colour is available at once, and so resulting in lower colour brightness and accuracy. Some developers have put a white segment for the colour wheel to improve all over brightness, but this also lessens colour accuracy.
I read in forums all the time that DLP has a higher contrast ratio and thus must be better. 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 able to produce. DLP projectors do offer high contrast specifications compared to most LCD projectors. At one glance, 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 while the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to project has moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector forms with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this disadvantage because the colours are sent simultaneously. DLP builders have formed 3DLP solutions using 3 chips to solve the colour break up problem, but the cost of these projectors make them impractical for most businesses and consumers.
Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Jump back to high school science, and remember how different colours of light refract differing amounts when projected through the same lens. The problem 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 different and refract light at different levels. Usually with a DLP projector, a superfluous yellow colour will be projected above and some extra blue will appear below an image as simple as a single black line. While being built LCD projectors can be fixed to take away these effects on the projected image, because each colour is processed on its own LCD panels.
The only true buy point (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant for mobility and has to be traded off against the image plusses of LCD projectors. If overall picture quality is vital to you, then the answer is easy. Go for an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image mistakes. If you want to know 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 at Projector Central, Australia’s premier online retailer for projectors. Brisbane based, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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