Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question that is asked when acquiring a new projector for the home, office, or classroom is: should I get an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two top projector imaging technologies. With so many business brands and different models available, it can be challenging for customers to choose between both technologies. The simple fact of the matter is that LCD projectors give better image quality and colour accuracy. The following article will tell you why DLP projectors struggle with projecting a similar grade of image quality.
It’s like a set of blinds in your room over your bedroom window. By twisting a rod you can make the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector works. Each pixel works like a single shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is made up 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 at which the projector is switched on to when the content reaches your screen is vitally significant with regard to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 separate LCD panels. The 3 LCD panels make the elements of the image by shining each pixel on and off. The pixels are then simultaneously processed in a glass prism to form the projector image. An important point to remember about LCD projectors is that all three colours are directed onto your projector screen at once. The way a DLP projector operates is widely different and even how an image appears is not the same. With DLP, white light from the lamp is sent through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to forming 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 form the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into a single total image. With LCD projectors, all colours are available all the time to form the highest brightness and great colour accuracy. In DLP, only one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP developers have included a white segment into the colour wheel to improve overall brightness, but this goes and detracts from colour accuracy.
I find in forums all the time that DLP offers a higher contrast ratio and as such must be better quality. For those who are 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 provide high contrast specifications as compared to the majority of LCD projectors. At one glance, this appears to be a plus, 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 fooled by contrast specifications on websites and in brochures.
When the content you are trying to bring to life includes moving images, DLP projection technology can also have image errors, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images keep changing between the time red, blue and green colours are pulled up. LCD projectors do not have this problem because all colours are sent at the same time. DLP manufacturers have developed 3DLP solutions using 3 chips to fix the colour break up problem, but the price of these projectors make them hardly practical for many businesses and consumers.
Another difference between LCD and DLP is how they make up for the refractive qualities of light. Take yourself back to high school science, and remember when they taught you how various colours of light refract differing amounts when shone through the same lens. The disadvantage 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 obviously different and refract light in a different way. Often with a DLP projector, some yellow colour will appear above and some extra blue will show below an image containing something as simple as a single black line. In building LCD projectors can be fixed to take away these effects on the projected image, because each colour is refracted on a separate LCD panels.
The one real buy point (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant to transporting the device and has to be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is vital to you, then the choice is easy. Take an LCD projector! LCD projectors will definitely make bright, colourful images with fewer image blips. If you need to learn more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any persisting questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s premier online provider 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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