Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question that is asked when purchasing a new projector for the home, office, or classroom is: would I get an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many brands and different types available, it can be confusing for the buyer to decide between the two technologies. The simple fact of the matter is that LCD projectors give far superior image quality and colour accuracy. The following article explains why DLP projectors struggle with projecting a similar level of image quality.
Imagine a set of blinds in your home on your bedroom window. By a twist of a rod you can turn the shutters open or closed, according to if you want to let light in or not. And that is exactly how an LCD projector works. Each pixel functions like a single 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 professionals like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the point at which the projector is turned on to when the image reaches your screen is vitally important for 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 send the coloured light to 3 stand alone LCD panels. The 3 LCD panels form the elements of the image by switching each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. Something to know about LCD projectors is that all three colours are directed onto your wall simultaneously. The way a DLP projector runs is totally different and even the way an image shows up is not the same. With DLP, white light from the lamp is processed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to creating an image creates 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 sent in sequence on the screen, one colour at a time. The viewer’s eye will then pull together each coloured element of the image into the single complete image. With LCD projectors, all colours are available all the time to offer the top level of brightness and superb colour accuracy. In DLP, just one colour is available at once, resulting in lower colour brightness and accuracy. Some designers have placed a white segment for the colour wheel to improve brightness generally, but this further detracts from colour accuracy.
I find in forums all the time that DLP offers a higher contrast ratio and as such must be better. 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 technology is able to produce. DLP projectors do offer high contrast specifications as compared to a majority of LCD projectors. Initially, this seems to be an advantage, however, in truth, the true black level is determined by the ambient light in the room when the projector is being utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to see has moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most typical artifact that a DLP projector displays 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 disadvantage because every colour is sent at the same time. DLP developers have formed 3DLP solutions using 3 chips to fix the colour break up issue, but the price of these projectors make them almost impossible for many businesses and consumers.
Another variance between LCD and DLP is how they balance for the refractive qualities of light. Jump 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 utilise the one same panel and the same lens to project Red, Blue and Green. All 3 colours are different and refract light at different levels. Often with a DLP projector, some yellow colour will show above and some extra blue will show below an image containing something as simple as a single black line. In manufacturing LCD projectors can be adjusted to remove these effects on the projected image, because each colour is directed on a separate LCD panels.
The one veritable benefit (excluding price) with picking a DLP projector is its smaller size and weight. However, this is only relevant with regard to transport and has to be traded off against the image plusses of LCD projectors. If overall picture quality is important to you, then the decision is a no-brainer. Go with an LCD projector! LCD projectors will always show bright, colourful images with fewer image mistakes. If you wish to ask more about LCD technology in more detail, check out this tremendous resource website: Explore 3LCD. If you have any additional questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s number one online shop for projectors. Based in Brisbane, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
Sphere: Related Content