Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question customers ask when buying a new projector for the home, office, or classroom is: do I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and different models available, it can be overwhelming for clients to make a decision between these technologies. Ultimately LCD projectors have far better image quality and colour accuracy. The next paragraph explains why DLP projectors struggle with creating an equal level of image quality.
It’s like a set of blinds in your room covering your bedroom window. By twisting a rod you can have the shutters open or closed, according to whether you want to let light in or not. That is exactly how an LCD projector works. Each pixel operates like a unique shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as pros 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 switches on to when the picture reaches your screen is extremely significant for image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 stand alone LCD panels. The 3 LCD panels form the elements of the image by switching each pixel on and off. The pixels are then projected in a glass prism to send the projector image. Something to remember about LCD projectors is that all three colours are directed onto your wall at once. The way a DLP projector operates is widely different and even the way 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 approach to creating an image forms a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to form the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s eyes will then put together each coloured element of the image into a full image. Using LCD projectors, all colours are available all the time to offer the best brightness and fantastic colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some DLP designers have placed a white segment for the colour wheel to improve overall brightness, but this goes and detracts from colour accuracy.
I read in forums all the time that DLP gives a higher contrast ratio and thus must be superior quality. For those who don’t 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 projector is able to produce. DLP projectors do possess high contrast specifications as compared to a majority of LCD projectors. At a glance, this can seem to be a plus, however, in real life, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to view requires moving images, DLP projection technology can also create image errors, or ‘artifacts’. The most typical artifact that a DLP projector shows with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change between the time red, blue and green colours are projected. LCD projectors do not have this downside because all colours are delivered simultaneously. DLP manufacturers have created 3DLP solutions using 3 chips to answer the colour break up problem, but the expense of these projectors make them impractical for many businesses and consumers.
Another point of difference between LCD and DLP is how they match the balance for the refractive qualities of light. Remember back to high school science, and remember how various colours of light refract differing amounts when shone through the same lens. The downfall 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 obviously different and refract light in different ways. Usually with a DLP projector, some extra yellow colour will show above and some blue will come up below something as simple as a single black line. In manufacturing LCD projectors can be adapted to take away these effects on the projected image, as each colour is refracted on a separate LCD panels.
The only actual advantage (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to mobility and must be traded off against the image superiority of LCD projectors. If the outcome of the picture quality is crucial to you, then the choice is a no-brainer. Take an LCD projector! LCD projectors will definitely make bright, colourful images with fewer image errors. If you desire to learn more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any more questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s number one online retailer for projectors. Brisbane based, Projector Central has served Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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