Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question customers ask when purchasing a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and different models available, it can be confusing for clients to choose between these technologies. The fact is that LCD projectors give better image quality and colour accuracy. The next part of this article will explain why DLP projectors struggle with reproducing a comparable grade of image quality.
Think of a set of blinds in your household for your bedroom window. By twisting a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. That is exactly how an LCD projector functions. Each pixel functions like a unique shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the professionals like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point when the projector is switched on to when the content reaches your screen is vitally important in regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by dividing it into red, blue and green components, by three mirrors which project the coloured light to 3 different LCD panels. The 3 LCD panels cast the elements of the image by turning each pixel on and off. The pixels are then meshed in a glass prism to send the projector image. An important point to understad about LCD projectors is that all three colours are sent onto your wall at once. The way a DLP projector runs is totally different and even the final product of how an image shows up 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 method of creating an image requires a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to form the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eye will then combine each coloured element of the image into a single full image. In LCD projectors, all colours are available all the time to form high brightness and great colour accuracy. In DLP, only one colour is available at a time, resulting in lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment in the colour wheel to improve all over brightness, but this goes and lessens colour accuracy.
I read in forums all the time that DLP has a higher contrast ratio and ergo must be superior quality. For those uncertain, 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 projector is capable of producing. DLP projectors do have high contrast specifications compared to most LCD projectors. At one glance, this seems to be an advantage, however, in truth, the true black level is determined by the ambient light in the room where the projector is in use. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to view has moving images, DLP projection technology can also have image errors, or ‘artifacts’. The most commonplace artifact that a DLP projector shows with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images keep changing between the time red, blue and green colours are displayed. LCD projectors do not have this downside because the colours are projected with the others. DLP developers have created 3DLP solutions using 3 chips to fix the colour break up issue, but the cost of these projectors make them almost impossible for the large part of businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and recall how the different colours of light refract various amounts when passing through the same lens. The downside with DLP projectors is that they use the one same panel and the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Generally with a DLP projector, some yellow colour will come through above and an extra blue will come up below an image containing something as simple as a lone black line. In building LCD projectors can be adjusted to minimize these effects on the projected image, because each colour is processed on a separate LCD panels.
The one true buy point (excluding price) with deciding on a DLP projector is its smaller size and weight. However, this is only relevant in regard to transporting the device and cannot be traded off against the image superiority of LCD projectors. If overall picture quality is crucial to you, then the decision is easy. Go for an LCD projector! LCD projectors will definitely produce bright, colourful images with fewer image mistakes. If you need to ask more about LCD technology in more detail, check out this tremendous resource website: Explore 3LCD. If you have any more 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 store for projectors. Based in Brisbane, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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