Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when looking for a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and models available, it can be challenging for the buyer to pick between both technologies. It comes down to the fact that LCD projectors offer far better image quality and colour accuracy. The next paragraph will tell you why DLP projectors struggle with creating a similar grade of image quality.
Visualise a set of blinds in your room over your bedroom window. With the twist of a rod you can turn 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 functions like an individual 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 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 is turned on to when the picture reaches your screen is ultimately significant in regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by separating it into red, blue and green components, by three mirrors which project the coloured light to 3 separate LCD panels. The 3 LCD panels cast the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to create the projector image. A significant point to know about LCD projectors is that all three colours are directed onto your wall at the same time. The way a DLP projector operates is vastly different and even how an image comes out is not the same. With DLP, white light from the lamp is projected through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of forming an image casts 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 sent in sequence on the screen, one colour at a time. The viewer’s vision will then pull together each coloured element of the image into a complete image. From LCD projectors, all colours are available all the time to offer the top level of brightness and great colour accuracy. In DLP, just one colour is available at any given time, causing lower colour brightness and accuracy. Some developers have put a white segment for the colour wheel to improve brightness overall, but this also damages colour accuracy.
I read in forums all the time that DLP provides a higher contrast ratio and thus must be superior. 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 machine is capable of producing. DLP projectors do provide high contrast specifications compared to the majority of LCD projectors. Initially, this must be a plus, however, in truth, the true black level is determined by the ambient light in the room while the projector is in use. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to bring to life includes moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most common artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change position between the time red, blue and green colours are pulled up. LCD projectors do not have this disadvantage because the colours are sent at once. DLP manufacturers have developed 3DLP solutions using 3 chips to solve the colour break up problem, but the cost of these projectors make them not practical for the large part of businesses and consumers.
Another point of difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and remember when they taught you how various colours of light refract varied amounts when passing through the same lens. The problem 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 not the same and refract light differently. Generally with a DLP projector, some extra yellow colour will be projected above and a spill of blue will come through below something as simple as a single black line. During manufacturing LCD projectors can be fixed to minimize these effects on the projected image, as each colour is directed on separate LCD panels.
The one actual buy point (excluding price) with going with a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to portability and cannot be traded off against the image plusses of LCD projectors. If resulting picture quality is crucial to you, then the choice is simple. Go with an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image errors. If you desire to know more about LCD technology in more detail, check out this fabulous resource website: Explore 3LCD. If you have any persisting questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s premier online store for projectors. Based in Brisbane, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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