Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question asked when buying a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two top projector imaging technologies. With so many different brands and types available, it can be confusing for clients to pick between both technologies. The simple fact of the matter is that LCD projectors offer far better image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with projecting a comparable standard of image quality.
It’s like a set of blinds in your home for your bedroom window. By twisting a rod you can turn the shutters open or closed, according to whether you want to let light in or not. That is exactly how an LCD projector functions. Each pixel works like a unique shutter on a set of blinds to either send light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as the professionals 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 switches on to when the picture reaches your screen is extremely significant in regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 different LCD panels. The 3 LCD panels make the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. A significant point to understad about LCD projectors is that all three colours are projected onto your projector screen simultaneously. The way a DLP projector functions is vastly different and even the produced image looks is not the same. With DLP, white light from the lamp is processed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of making an image casts a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to produce the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eye will then put together each coloured element of the image into the whole image. With LCD projectors, all colours are available all the time to form the best brightness and great colour accuracy. In DLP, only one colour is available at once, causing lower colour brightness and accuracy. Some developers have placed a white segment for the colour wheel to improve all over brightness, but this further degrades colour accuracy.
I see in forums all the time that DLP gives a higher contrast ratio and therefore must be better quality. For those unsure, 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 system is capable of producing. DLP projectors do provide high contrast specifications as compared to a majority of LCD projectors. At first glance, this must be a benefit, however, in real life, 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 plan to project includes moving images, DLP projection technology also creates image marks, or ‘artifacts’. The most typical artifact that a DLP projector displays with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this downside because all the colours are delivered with the others. DLP manufacturers have created 3DLP solutions using 3 chips to fix the colour break up issue, but the price tag of these projectors make them not practical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they make up for the refractive qualities of light. Remember back to high school science, and they taught you how the different colours of light refract differing amounts when directed through the same lens. The disadvantage with DLP projectors is that they have the one same panel for the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Most of the time with a DLP projector, a spill of yellow colour will show above and a spill of blue will come through below something as simple as a straight black line. During manufacturing LCD projectors can be fixed to minimize these effects on the projected image, because each colour is directed on a separate LCD panels.
The isolated true benefit (excluding price) with going with a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to mobility and must be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is crucial to you, then the solution is easy. Take an LCD projector! LCD projectors will definitely create bright, colourful images with fewer image mistakes. If you desire to ask more about LCD technology in more detail, have a look at this fantastic 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 of Projector Central, Australia’s leading online provider for projectors. Brisbane based, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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