The most typical question heard when looking for a new projector for the home, office, or classroom is: do I purchase an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and different types available, it can be overwhelming for the buyer to make a decision between these technologies. It comes down to the fact that LCD projectors give far better image quality and colour accuracy. The next part of this article will explain why DLP projectors struggle with bringing up a similar standard of image quality.
It’s like a set of blinds in your household for your bedroom window. By a 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 functions like its own shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as professionals 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 turns on to when the content reaches your screen is vitally important in regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by cutting it into red, blue and green components, by three mirrors which direct the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then projected in a glass prism to send the projector image. Something to realise about LCD projectors is that all three colours are directed onto your screen at the same time. The way a DLP projector runs is very different and even how an image appears is not the same. With DLP, white light from the lamp is projected through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image requires a sequence of red, blue and green light. The millions of micro mirrors described 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 vision will then put together each coloured element of the image into the full image. With LCD projectors, all colours are available all the time to form the top level of brightness and great colour accuracy. In DLP, only one colour is available at a time, causing lower colour brightness and accuracy. Some developers have placed a white segment for the colour wheel to improve overall brightness, but this further detracts from colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and as such must be better quality. For those who do not 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 technology is able to produce. DLP projectors do have high contrast specifications compared to the majority of LCD projectors. At one glance, this appears 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 duped by contrast specifications on websites and in brochures.
When the content you wish to view includes moving images, DLP projection technology also creates image marks, or ‘artifacts’. The most common artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change position between the time red, blue and green colours are displayed. LCD projectors do not have this disadvantage because the colours are projected at once. DLP builders have formed 3DLP solutions using 3 chips to answer the colour break up problem, but the expense of these projectors make them not practical for the majority of 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 when they taught you how various colours of light refract varied amounts when projected through the same lens. The disadvantage with DLP projectors is that they take the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously not the same and refract light differently. Often with a DLP projector, some yellow colour will come through above and a spill of blue will appear below an image containing something as simple as a straight black line. In building LCD projectors can be fixed to minimize these effects on the projected image, as each colour is directed on its own LCD panels.
The sole actual plus (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant with regard to transporting the device and needs to be traded off against the image superiority of LCD projectors. If overall picture quality is vital to you, then the answer is simple. Choose an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image mistakes. If you need to find out more about LCD technology in more detail, have a look at this tremendous resource website: Explore 3LCD. If you have any additional questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s premier online provider for projectors. Brisbane based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
Tags: data projectors brisbane, data projectors gold coastJuly 19th, 2010UncategorizedRead More >No Comments
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