The most common question asked when purchasing a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and different types available, it can be difficult for consumers to choose between those technologies. Ultimately LCD projectors give better image quality and colour accuracy. The following article tells you why DLP projectors struggle with reproducing a comparable standard of image quality.
It’s like a set of blinds in your house for your bedroom window. With the twist of a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. And that is exactly how an LCD projector works. Each pixel operates like a single shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the point when the projector switches on to when the image reaches your screen is vitally significant with regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by splitting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then combined in a glass prism to form the projector image. Something to know about LCD projectors is that all three colours are projected onto your projector screen simultaneously. The way a DLP projector works is very different and even the final product of how an image shows up is not the same. With DLP, white light from the lamp is processed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to making 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 create the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into a single total image. With LCD projectors, all colours are available all the time to form high brightness and spectacular colour accuracy. In DLP, only one colour is available at once, causing lower colour brightness and accuracy. Some designers have added a white segment into the colour wheel to improve overall brightness, but this also degrades colour accuracy.
I read in forums all the time that DLP has a higher contrast ratio and ergo must be better quality. For those who don’t know, 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 producing. DLP projectors do possess high contrast specifications compared to many LCD projectors. Initially, this must be an advantage, however, in reality, the true black level is determined by the ambient light in the room where the projector is in use. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you are trying to project includes moving images, DLP projection technology also creates image errors, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this problem because every colour is projected with the others. DLP developers have formed 3DLP solutions using 3 chips to fix the colour break up issue, but the expense of these projectors make them almost impossible for many businesses and consumers.
Another point of difference between LCD and DLP is how they make up for the refractive qualities of light. Remember back to high school science, and remember when they taught you how different colours of light refract different amounts when shone through the same lens. The downside with DLP projectors is that they utilise the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Generally with a DLP projector, some yellow colour will be projected above and an extra blue will appear below something as simple as a straight black line. While being built LCD projectors can be set to minimize these effects on the projected image, as each colour is refracted on separate LCD panels.
The one real plus (excluding price) with going with a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to transporting the device and must be traded off against the image superiority of LCD projectors. If the result of the picture quality is crucial to you, then the choice is simple. Go for an LCD projector! LCD projectors will always make bright, colourful images with fewer image blips. If you wish to find out more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any persisting questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online store for projectors. Brisbane based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
Tags: data projectors brisbane, data projectors gold coastJuly 19th, 2010UncategorizedRead More >No Comments