The most typical question heard when purchasing a new projector for the home, office, or classroom is: would I purchase 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 most common projector imaging technologies. With so many company brands and different models available, it can be challenging for clients to pick between both technologies. Ultimately LCD projectors have superior image quality and colour accuracy. The following article will tell you why DLP projectors struggle with reproducing the same grade of image quality.
Visualise a set of blinds in your house covering your bedroom window. By a twist of a rod you can have the shutters open or closed, depending on whether you want to let light in or not. And this is exactly how an LCD projector works. Each pixel operates like an individual 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 the pros like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the time the projector is switched on to when the content reaches your screen is vitally important for image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by separating it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels create the elements of the image by turning each pixel on and off. The pixels are then combined in a glass prism to form the projector image. A point to understad about LCD projectors is that all three colours are delivered onto your screen at once. The way a DLP projector works is very different and even the final product of how an image comes out is not the same. With DLP, white light from the lamp is projected through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to forming 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 displayed in sequence on the screen, one colour at a time. The viewer’s vision will then draw each coloured element of the image into a whole image. With LCD projectors, all colours are available all the time to offer the top level of brightness and superb colour accuracy. In DLP, only one colour is available at a time, and so causing lower colour brightness and accuracy. Some DLP manufacturers have added a white segment into the colour wheel to improve brightness generally, but this then damages colour accuracy.
I see in forums all the time that DLP provides a higher contrast ratio and thus must be better 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 system is capable of producing. DLP projectors do possess high contrast specifications in comparison to a majority of LCD projectors. At one glance, this seems to be an advantage, however, in reality, the true black level is determined by the ambient light in the room while the projector is used. Do not be fooled by contrast specifications on websites and in brochures.
When the content you want to project has moving images, DLP projection technology also creates image marks, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change up between the time red, blue and green colours are pulled up. LCD projectors do not have this problem because all colours are projected with the others. DLP manufacturers have formed 3DLP solutions using 3 chips to fix the colour break up artifacts, but the price tag of these projectors make them hardly practical for the large part of businesses and consumers.
Another variance between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and recall when they taught you how various colours of light refract different amounts when passing through the same lens. The downfall 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 not the same and refract light at different levels. Often with a DLP projector, a spill of yellow colour will come up above and a superfluous blue will be projected below an image as simple as a straight black line. In manufacturing LCD projectors can be adjusted to minimize these effects on the projected image, because each colour is processed on isolated LCD panels.
The one veritable benefit (excluding price) with buying a DLP projector is its smaller size and weight. However, this is only relevant for portability and cannot be traded off against the image advantages of LCD projectors. If overall picture quality is important to you, then the choice is no-brainer. Choose an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you wish to ask more about LCD technology in more detail, have a gander at this spectacular resource website: Explore 3LCD. If you have any further questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s leading online retailer for projectors. Brisbane-based, Projector Central has served Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.