Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question heard when purchasing a new projector for the home, office, or classroom is: do I purchase an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most common projector imaging technologies. With so many brands and models available, it can be overwhelming for consumers to make a choice between those technologies. Ultimately LCD projectors give better image quality and colour accuracy. The article below explains why DLP projectors struggle with reproducing an equal standard of image quality.
Visualise a set of blinds in your room for your bedroom window. By pulling on a rod you can make the shutters open or closed, depending on whether you want to let light in or not. That 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 constructed of millions of microscopic mirrors or ‘pixel elements’ as pros 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 switches on to when the content reaches your screen is ultimately important with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by dividing 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 shining each pixel on and off. The pixels are then meshed in a glass prism to send the projector image. A point to understad about LCD projectors is that all three colours are projected onto your screen at the same time. The way a DLP projector functions is vastly different and even the way an image appears is not the same. With DLP, white light from the lamp is projected through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to projecting 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 construct the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eyes will then pull together each coloured element of the image into a single total image. With LCD projectors, all colours are available all the time to offer the highest brightness and great colour accuracy. In DLP, only one colour is available at any given time, causing lower colour brightness and accuracy. Some DLP designers have added a white segment into the colour wheel to improve general brightness, but this further detracts from colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and as such must be better quality. For those who are unaware, 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. DLP projectors do provide high contrast specifications compared to a majority of LCD projectors. At first glance, this appears to be a plus, however, in the real world, the true black level is determined by the ambient light in the room in which the projector is utilised. Do not be duped by contrast specifications on websites and in brochures.
When the content you wish to bring to life requires moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector shows with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this downside because all colours are delivered at once. DLP developers have developed 3DLP solutions using 3 chips to answer the colour break up issue, but the price of these projectors make them hardly practical for most businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and remember when they taught you how different colours of light refract varied amounts when projected through the same lens. The problem with DLP projectors is that they have the one same panel for the same lens to project Red, Blue and Green. All 3 colours are different and refract light differently. Usually with a DLP projector, some extra yellow colour will be projected above and some extra blue will appear below something as simple as a lone black line. In manufacturing LCD projectors can be set to remove these effects on the projected image, because each colour is directed on separate LCD panels.
The sole veritable benefit (excluding price) with deciding on a DLP projector is its smaller size and weight. However, this is only relevant for mobility and has to be traded off against the image advantages of LCD projectors. If the result of the picture quality is vital to you, then the answer is no-brainer. Choose an LCD projector! LCD projectors will consistently make bright, colourful images with fewer image errors. If you wish to ask more about LCD technology in more detail, have a gander at this fantastic resource website: Explore 3LCD. If you have any persisting questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s premier online retailer for projectors. Brisbane based, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.