Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question customers ask 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, short for ‘digital light processing’ are the two top projector imaging technologies. With so many brands and different models available, it can be challenging for customers to choose between these technologies. The simple fact of the matter is that LCD projectors offer superior image quality and colour accuracy. The article below explains why DLP projectors struggle with creating a similar level of image quality.
Visualise a set of blinds in your house on your bedroom window. By pulling on a rod you can make the shutters open or closed, according to whether you want to let light in or not. That is exactly how an LCD projector operates. Each pixel works like a single shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point at which the projector is turned on to when the content reaches your screen is ultimately important for 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 individual LCD panels. The 3 LCD panels form the elements of the image by shining each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. A point to understad about LCD projectors is that all three colours are projected onto your screen all at the same time. The way a DLP projector functions is widely different and even how an image appears is not the same. With DLP, white light from the lamp is sent through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to creating an image forms a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to form the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into a full image. From LCD projectors, all colours are available all the time to deliver the top level of brightness and fantastic colour accuracy. In DLP, only one colour is available at any given time, resulting in lower colour brightness and accuracy. Some manufacturers have included a white segment into the colour wheel to improve general brightness, but this then lessens colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and ergo must be superior quality. For those who are uncertain, 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 have high contrast specifications as compared to many LCD projectors. At a glance, this can seem to be an advantage, however, in real life, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be duped by contrast specifications on websites and in brochures.
When the content you want to project needs moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most often seen 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 between the time red, blue and green colours are projected. LCD projectors do not have this downside because every colour is sent at the same time. DLP manufacturers have formed 3DLP solutions using 3 chips to resolve the colour break up error, but the cost of these projectors make them not practical for many businesses and consumers.
Another variance between LCD and DLP is how they make up for the refractive qualities of light. Take yourself back to high school science, and they taught you how various colours of light refract differing amounts when shone through the same lens. The disadvantage with DLP projectors is that they utilise 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 differently. Often with a DLP projector, a spill of yellow colour will come up above and a spill of blue will come up below an image of something as simple as a straight black line. In manufacturing LCD projectors can be fixed to minimize these effects on the projected image, because each colour is processed on isolated LCD panels.
The only true plus (excluding price) with deciding on a DLP projector is its smaller overall size and weight. However, this is only relevant to mobility and cannot be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is crucial to you, then the solution is simple. Take an LCD projector! LCD projectors will always create bright, colourful images with fewer image errors. If you wish to learn more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any other questions, jump onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s number one online retailer 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.
