Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question asked when looking for a new projector for the home, office, or classroom is: will I take an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many brands and models available, it can be challenging for clients to choose between the two technologies. The simple fact of the matter is that LCD projectors offer superior image quality and colour accuracy. The next paragraph will tell you why DLP projectors struggle with bringing up an equal grade of image quality.
Visualise a set of blinds in your room for your bedroom window. By pulling on a rod you can turn the shutters open or closed, according to whether you want to let light in or not. And this is exactly how an LCD projector functions. Each pixel operates 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 works to either reflect light or block it.
How the light source is processed from the time the projector turns on to when the content reaches your screen is ultimately significant in 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 transfer the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by processing each pixel on and off. The pixels are then simultaneously processed in a glass prism to send the projector image. Something to understad about LCD projectors is that all three colours are projected onto your projected surface all at the same time. The way a DLP projector functions is very different and even how an image comes out 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 casts a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to create the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into a single whole image. In LCD projectors, all colours are available all the time to create the top level of brightness and superb colour accuracy. In DLP, only one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP developers have placed a white segment in the colour wheel to improve brightness generally, but this goes and damages colour accuracy.
I find in forums all the time that DLP gives a higher contrast ratio and as such must be better 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 system is able to produce. DLP projectors do provide high contrast specifications in comparison to most LCD projectors. At one glance, this can seem to be a benefit, however, in reality, the true black level is determined by the ambient light in the room in which the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to view includes moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is inherent in DLP systems because moving images keep changing between the time red, blue and green colours are shone. LCD projectors do not have this downside because all colours are sent with the others. DLP developers have created 3DLP solutions using 3 chips to answer the colour break up issue, but the expense of these projectors make them hardly practical for the majority of businesses and consumers.
Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and remember when they taught you how the various colours of light refract varied amounts when directed through the same lens. The downfall 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 be projected above and some extra blue will show below an image of something as simple as a lone black line. While being built LCD projectors can be adapted to remove these effects on the projected image, because each colour is directed on isolated LCD panels.
The only actual advantage (excluding price) with picking a DLP projector is its smaller size and weight. However, this is only relevant for transport and must be traded off against the image benefits of LCD projectors. If overall picture quality is vital to you, then the solution is a no-brainer. Go for an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image mistakes. If you want to ask more about LCD technology in more detail, have a gander at this tremendous resource website: Explore 3LCD. If you have any other questions, get onto 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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