Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question customers ask when buying a new projector for the home, office, or classroom is: will I take an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most common projector imaging technologies. With so many company brands and models available, it can be overwhelming for clients to make a decision between those technologies. The simple fact of the matter is that LCD projectors give better image quality and colour accuracy. The article below will tell you why DLP projectors struggle with projecting a similar standard of image quality.
It’s like a set of blinds in your household over your bedroom window. By twisting a rod you can turn the shutters open or closed, depending on if you want to let light in or not. Such is exactly how an LCD projector behaves. Each pixel works like a single shutter on a set of blinds to either send light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the experts like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the time the projector switches on to when the picture reaches your screen is absolutely important with regard to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by dividing it into red, blue and green components, by three mirrors which send the coloured light to 3 stand alone LCD panels. The 3 LCD panels cast the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. Something important to know about LCD projectors is that all three colours are delivered onto your wall at once. The way a DLP projector functions is totally different and even the way an image comes out is not the same. With DLP, white light from the lamp is processed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image requires a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to produce the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s eyes will then pull together each coloured element of the image into the complete image. In LCD projectors, all colours are available all the time to offer the best brightness and fantastic colour accuracy. In DLP, only one colour is available at once, causing lower colour brightness and accuracy. Some developers have placed a white segment in the colour wheel to improve brightness generally, but this also damages colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and therefore must be superior quality. For those who do not 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 system is capable of. DLP projectors do provide high contrast specifications when compared to many LCD projectors. At a glance, this can seem to be a benefit, however, in truth, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you are trying to view needs moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most commonplace artifact that a DLP projector shows with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change position between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because every colour is delivered simultaneously. DLP developers have created 3DLP solutions using 3 chips to fix the colour break up error, but the price of these projectors make them impractical for many businesses and consumers.
Another difference between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and they taught you how different colours of light refract differing amounts when projected through the same lens. The downside with DLP projectors is that they have the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light at different levels. Often with a DLP projector, a spill of yellow colour will show above and an extra blue will come up below an image of something as simple as a single black line. In building LCD projectors can be fixed to remove these effects on the projected image, because each colour is processed on separate LCD panels.
The one veritable buy point (excluding price) with picking a DLP projector is its smaller total size and weight. However, this is only relevant with regard to portability and must be traded off against the image plusses of LCD projectors. If overall picture quality is important to you, then the solution is easy. Go with an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you want to learn more about LCD technology in more detail, see this fabulous resource website: Explore 3LCD. If you have any other 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 shop for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
