Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question heard when looking for a new projector for the home, office, or classroom is: will 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 common projector imaging technologies. With so many business brands and models available, it can be difficult for customers to pick between the two technologies. Ultimately LCD projectors offer far better image quality and colour accuracy. The article below will explain why DLP projectors struggle with creating the same level of image quality.
Imagine a set of blinds in your room over your bedroom window. By pulling a rod you can turn the shutters open or closed, depending on if you want to let light in or not. This is exactly how an LCD projector behaves. Each pixel works like its own shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is made up 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 picture reaches your screen is absolutely important to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by separating it into red, blue and green components, by three mirrors which direct 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 form the projector image. A point to remember about LCD projectors is that all three colours are projected onto your screen at the same time. The way a DLP projector operates is very different and even the produced image looks is not the same. With DLP, white light from the lamp is processed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to forming 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 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 combine each coloured element of the image into the full image. With LCD projectors, all colours are available all the time to create high brightness and spectacular colour accuracy. In DLP, only one colour is available at any given time, resulting in lower colour brightness and accuracy. Some DLP designers have put a white segment in the colour wheel to improve overall brightness, but this goes and lessens colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and therefore must be better. 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 possess high contrast specifications as compared to many LCD projectors. At a glance, this must be a benefit, however, in reality, the true black level is determined by the ambient light in the room in which the projector is being utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you are trying to see has moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images keep changing between the time red, blue and green colours are shone. LCD projectors do not have this problem because all colours are processed simultaneously. DLP manufacturers have developed 3DLP solutions using 3 chips to fix the colour break up artifacts, but the expense of these projectors make them not practical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Take yourself back to high school science, and remember how different colours of light refract various amounts when passing through the same lens. The problem with DLP projectors is that they take the one same panel for the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Often with a DLP projector, some yellow colour will show above and an extra blue will appear below an image containing something as simple as a lone black line. While being built LCD projectors can be adapted to take away these effects on the projected image, as each colour is refracted on separate LCD panels.
The sole actual benefit (excluding price) with deciding on a DLP projector is its smaller overall size and weight. However, this is only relevant with regard to transporting the device and must be traded off against the image benefits of LCD projectors. If resulting picture quality is crucial to you, then the solution is easy. Choose an LCD projector! LCD projectors will constantly produce bright, colourful images with fewer image blips. If you want to learn more about LCD technology in more detail, have a gander at this tremendous resource website: Explore 3LCD. If you have any persisting questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s leading online shop for projectors. Brisbane based, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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