Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question that is asked when purchasing a new projector for the home, office, or classroom is: should I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many company brands and models available, it can be overwhelming for consumers to make a choice between these technologies. The simple fact of the matter is that LCD projectors provide far better image quality and colour accuracy. The next paragraph tells you why DLP projectors struggle with creating an equal standard of image quality.
Imagine a set of blinds in your household over your bedroom window. By pulling a rod you can make the shutters open or closed, according to if you want to let light in or not. And this is exactly how an LCD projector operates. Each pixel functions 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 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 turns on to when the picture reaches your screen is extremely significant with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 separate LCD panels. The 3 LCD panels create the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to create the projector image. An important point to understad about LCD projectors is that all three colours are sent onto your projector screen at once. The way a DLP projector runs is very different and even the way an image shows up is not the same. With DLP, white light from the lamp is projected through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to forming an image creates 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 the full image. In LCD projectors, all colours are available all the time to deliver the best brightness and fantastic colour accuracy. In DLP, just one colour is available at a time, and so resulting in lower colour brightness and accuracy. Some manufacturers have placed a white segment in the colour wheel to improve brightness overall, but this further degrades colour accuracy.
I see in forums all the time that DLP offers a higher contrast ratio and thus must be better. For those 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 possess high contrast specifications when compared to the majority of LCD projectors. At a 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 tricked by contrast specifications on websites and in brochures.
When the content you plan to project includes moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most common 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 position between the time red, blue and green colours are projected. LCD projectors do not have this disadvantage because all the colours are delivered at once. DLP manufacturers have created 3DLP solutions using 3 chips to solve the colour break up artifacts, but the price of these projectors make them not practical for most 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 the different colours of light refract various amounts when shone through the same lens. The downside with DLP projectors is that they have the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in different ways. Most of the time with a DLP projector, some yellow colour will come up above and some blue will come through below something as simple as a straight black line. In building LCD projectors can be fixed to reduce these effects on the projected image, as each colour is directed on separate LCD panels.
The only actual advantage (excluding price) with buying a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to transport and cannot be traded off against the image advantages of LCD projectors. If resulting picture quality is important to you, then the choice is a no-brainer. Go with an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you desire to know more about LCD technology in more detail, have a look at this fabulous 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 at Projector Central, Australia’s number one online store for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.