Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question heard when acquiring a new projector for the home, office, or classroom is: should I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two top projector imaging technologies. With so many business brands and different models available, it can be difficult for the buyer to make a choice between both technologies. The fact is that LCD projectors give far better image quality and colour accuracy. The next part of this article will tell you why DLP projectors struggle with bringing up a comparable level of image quality.
Visualise a set of blinds in your home over your bedroom window. With the twist of a rod you can have the shutters open or closed, according to if you want to let light in or not. Such is exactly how an LCD projector works. Each pixel works like a single shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as 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 absolutely important for image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 stand alone LCD panels. The 3 LCD panels create 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 understad about LCD projectors is that all three colours are directed onto your screen simultaneously. The way a DLP projector works is vastly different and even the produced image appears 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 way 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 produce the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s vision will then draw each coloured element of the image into a complete image. In LCD projectors, all colours are available all the time to offer high brightness and great colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment for the colour wheel to improve brightness overall, but this then lessens colour accuracy.
I read in forums all the time that DLP has a higher contrast ratio and thus must be better quality. For those who are 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 technology is able to produce. DLP projectors do offer high contrast specifications compared to the majority of LCD projectors. At a glance, this seems to be a benefit, however, in truth, the true black level is determined by the ambient light in the room while the projector is being utilised. Do not be fooled by contrast specifications on websites and in brochures.
When the content you want to view includes moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most often seen artifact that a DLP projector forms with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images keep changing between the time red, blue and green colours are pulled up. LCD projectors do not have this characteristic because all the colours are processed with the others. DLP builders have formed 3DLP solutions using 3 chips to solve the colour break up error, but the cost of these projectors make them almost impossible for many businesses and consumers.
Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Remember back to high school science, and remember how the various colours of light refract various amounts when directed through the same lens. The problem with DLP projectors is that they take the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light differently. Most of the time with a DLP projector, an extra yellow colour will show above and an extra blue will appear below an image as simple as a straight black line. During manufacturing LCD projectors can be adapted to take away these effects on the projected image, because each colour is refracted on its own LCD panels.
The only veritable advantage (excluding price) with going with a DLP projector is its smaller size and weight. However, this is only relevant to mobility and needs to be traded off against the image plusses of LCD projectors. If overall picture quality is important to you, then the decision is no-brainer. Take an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image blips. If you desire to ask more about LCD technology in more detail, see this fabulous resource website: Explore 3LCD. If you have any other questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s number one online retailer for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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