Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question heard when buying a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and models available, it can be overwhelming for customers to pick between the two technologies. The simple fact of the matter is that LCD projectors give far better image quality and colour accuracy. The next paragraph explains why DLP projectors struggle with projecting a comparable grade of image quality.
It’s like a set of blinds in your home on 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. Such is exactly how an LCD projector behaves. Each pixel operates like its own shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as pros 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 switched on to when the image reaches your screen is absolutely important for image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by dividing 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 shining each pixel on and off. The pixels are then projected in a glass prism to send the projector image. Something to realise about LCD projectors is that all three colours are sent onto your screen at once. The way a DLP projector works is widely different and even the final product of how an image looks 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 approach to making an image requires 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 projected in sequence on the screen, one colour at a time. The viewer’s eyes will then combine each coloured element of the image into the full image. From LCD projectors, all colours are available all the time to offer top brightness and superb colour accuracy. In DLP, only one colour is available at any given time, and so causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment in the colour wheel to improve brightness overall, but this goes and detracts from colour accuracy.
I hear in forums all the time that DLP has a higher contrast ratio and as such 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 many LCD projectors. At first glance, this can seem to be an advantage, however, in real life, 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 plan to project includes moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most often seen artifact that a DLP projector shows 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 pulled up. LCD projectors do not have this characteristic because every colour is projected with the others. DLP manufacturers have come up with 3DLP solutions using 3 chips to answer the colour break up problem, but the price tag of these projectors make them almost impossible for many businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Remember back to high school science, and remember when they taught you how different colours of light refract varied amounts when projected through the same lens. The downside with DLP projectors is that they take the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light differently. Often with a DLP projector, a superfluous yellow colour will come up above and a spill of blue will show below an image of something as simple as a lone black line. During manufacturing LCD projectors can be fixed to remove these effects on the projected image, because each colour is directed on a separate LCD panels.
The sole true plus (excluding price) with picking a DLP projector is its smaller size and weight. However, this is only relevant with regard to transporting the device 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 no-brainer. Take an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you want to ask more about LCD technology in more detail, check out this tremendous resource website: Explore 3LCD. If you have any further questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s leading online shop for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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