Mack and Mark

The most typical question heard when acquiring a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two most popular projector imaging technologies. With so many business brands and types available, it can be overwhelming for customers to make a decision between those technologies. The simple fact of the matter is that LCD projectors offer far better image quality and colour accuracy. The article below explains why DLP projectors struggle with projecting an equal level of image quality.

Think of a set of blinds in your room over your bedroom window. By a twist of a rod you can make the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector operates. Each pixel operates like a single shutter on a set of blinds to either allow 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 is turned on to when the content reaches your screen is ultimately significant with regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by cutting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels make the elements of the image by shining each pixel on and off. The pixels are then simultaneously processed in a glass prism to form the projector image. A point to know about LCD projectors is that all three colours are projected onto your wall at once. The way a DLP projector operates is totally different and even the way an image appears 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 method of projecting 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 form the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s vision will then put together each coloured element of the image into a single full image. Using LCD projectors, all colours are available all the time to form the top level of brightness and superb colour accuracy. In DLP, just one colour is available at a time, and so causing lower colour brightness and accuracy. Some DLP manufacturers have included a white segment into the colour wheel to improve general brightness, but this then degrades colour accuracy.

I hear in forums all the time that DLP has a higher contrast ratio and thus must be superior 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 have high contrast specifications in comparison to many LCD projectors. At first glance, this appears to be a benefit, however, in truth, the true black level is determined by the ambient light in the room while the projector is utilised. Do not be duped by contrast specifications on websites and in brochures.

When the content you wish to see includes moving images, DLP projection technology can also have image errors, or ‘artifacts’. The most common artifact that a DLP projector forms with moving images is colour break up. Colour break up is incontrovertible 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 the colours are projected with the others. DLP manufacturers have developed 3DLP solutions using 3 chips to answer the colour break up problem, but the cost 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. Think back to high school science, and remember how various colours of light refract differing amounts when passing through the same lens. The downfall with DLP projectors is that they use the one same panel for the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light differently. Most of the time with a DLP projector, an extra yellow colour will show above and a spill of blue will show below an image of something as simple as a straight black line. During manufacturing LCD projectors can be adjusted to remove these effects on the projected image, as each colour is processed on its own LCD panels.

The only true plus (excluding price) with taking a DLP projector is its smaller size and weight. However, this is only relevant to mobility and has to be traded off against the image advantages of LCD projectors. If the outcome of the picture quality is crucial to you, then the solution is easy. Go for an LCD projector! LCD projectors will definitely create bright, colourful images with fewer image errors. If you desire to know more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any additional questions, go to 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 been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.