Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when purchasing a new projector for the home, office, or classroom is: should I purchase an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many different brands and types available, it can be overwhelming for the buyer to make a choice between those technologies. It comes down to the fact that LCD projectors provide far better image quality and colour accuracy. The article below explains why DLP projectors struggle with projecting an equal standard of image quality.
It’s like a set of blinds in your house over your bedroom window. With the twist of a rod you can turn the shutters open or closed, according to whether you want to let light in or not. This is exactly how an LCD projector operates. Each pixel functions like an individual shutter on a set of blinds to either send 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 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 shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 stand alone LCD panels. The 3 LCD panels make the elements of the image by switching each pixel on and off. The pixels are then projected in a glass prism to form the projector image. A point to know about LCD projectors is that all three colours are directed onto your wall simultaneously. The way a DLP projector functions is very different and even the produced image appears 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 method of creating an image forms a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to form the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s eyes will then put together each coloured element of the image into a single complete image. In LCD projectors, all colours are available all the time to form top brightness and spectacular colour accuracy. In DLP, just one colour is available at once, resulting in lower colour brightness and accuracy. Some designers have put a white segment into the colour wheel to improve all over brightness, but this further detracts from colour accuracy.
I hear in forums all the time that DLP gives a higher contrast ratio and therefore must be superior. 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 technology is capable of. DLP projectors do provide high contrast specifications in comparison to the majority of LCD projectors. At first glance, this must be a benefit, however, in truth, the true black level is determined by the ambient light in the room in which the projector is being utilised. Do not be duped by contrast specifications on websites and in brochures.
When the content you want to view requires moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most common artifact that a DLP projector displays with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images keep changing between the time red, blue and green colours are projected. LCD projectors do not have this downside because every colour is processed at the same time. DLP manufacturers have developed 3DLP solutions using 3 chips to solve the colour break up problem, but the expense of these projectors make them not practical for the large part of businesses and consumers.
Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Jump 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 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 not the same and refract light at different levels. Most of the time with a DLP projector, some extra yellow colour will appear above and a spill of blue will come up below an image containing something as simple as a single black line. During manufacturing LCD projectors can be adjusted to reduce these effects on the projected image, because each colour is projected on its own LCD panels.
The sole true benefit (excluding price) with buying a DLP projector is its overall smaller size and weight. However, this is only relevant to portability and has to be traded off against the image advantages of LCD projectors. If the result of the picture quality is crucial to you, then the solution is simple. Go with an LCD projector! LCD projectors will consistently show bright, colourful images with fewer image imperfections. If you wish to ask more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any additional questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s number one online retailer for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
Sphere: Related Content