Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question heard when looking for a new projector for the home, office, or classroom is: do I get an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and models available, it can be confusing for the buyer to make a choice between those technologies. The fact is that LCD projectors give better image quality and colour accuracy. The article below explains why DLP projectors struggle with reproducing the same standard of image quality.
It’s like a set of blinds in your room 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. And this is exactly how an LCD projector works. Each pixel works like its own shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is constructed 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 the time the projector is switched on to when the image reaches your screen is ultimately important in regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 different LCD panels. The 3 LCD panels form the elements of the image by shining each pixel on and off. The pixels are then meshed in a glass prism to create the projector image. A significant point to realise about LCD projectors is that all three colours are projected onto your projected surface all at once. The way a DLP projector works is totally different and even the way an image comes out is not the same. With DLP, white light from the lamp is directed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of forming an image forms a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to construct 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 complete image. With LCD projectors, all colours are available all the time to deliver top brightness and superb colour accuracy. In DLP, only one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some manufacturers have included a white segment for the colour wheel to improve brightness generally, but this goes and lessens colour accuracy.
I read in forums all the time that DLP gives a higher contrast ratio and thus must be superior 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 machine is capable of producing. DLP projectors do provide high contrast specifications as compared to many LCD projectors. At one glance, this appears to be a benefit, however, in the real world, the true black level is determined by the ambient light in the room where the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you want to see has moving images, DLP projection technology can also create image marks, or ‘artifacts’. The most commonplace artifact that a DLP projector shows 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 pulled up. LCD projectors do not have this disadvantage because every colour is sent with the others. DLP designers have created 3DLP solutions using 3 chips to answer the colour break up issue, but the price tag 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. Think back to high school science, and remember how the different colours of light refract various amounts when directed through the same lens. The problem with DLP projectors is that they use the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously not the same and refract light in a different way. Often with a DLP projector, some yellow colour will be projected above and a spill of blue will show below an image as simple as a lone black line. In manufacturing LCD projectors can be adjusted to take away these effects on the projected image, as each colour is processed on separate LCD panels.
The sole actual advantage (excluding price) with deciding on a DLP projector is its smaller size and weight. However, this is only relevant in regard to transporting the device and has to be traded off against the image benefits of LCD projectors. If overall picture quality is crucial to you, then the answer is no-brainer. Go with an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image errors. If you need to learn more about LCD technology in more detail, have a gander at this fantastic resource website: Explore 3LCD. If you have any more questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s premier online provider for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
