Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question asked when looking for a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most popular projector imaging technologies. With so many business brands and different types available, it can be overwhelming for the buyer to decide between those technologies. The simple fact of the matter is that LCD projectors offer superior image quality and colour accuracy. The article below will explain why DLP projectors struggle with creating a similar standard of image quality.
It’s like a set of blinds in your household on your bedroom window. By twisting a rod you can turn the shutters open or closed, according to whether you want to let light in or not. Such is exactly how an LCD projector behaves. Each pixel works like a unique shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as the pros 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 switched on to when the content reaches your screen is absolutely significant to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by separating it into red, blue and green components, by three mirrors which send the coloured light to 3 separate LCD panels. The 3 LCD panels make the elements of the image by switching each pixel on and off. The pixels are then projected in a glass prism to form the projector image. A point to remember about LCD projectors is that all three colours are directed onto your projected surface all at once. The way a DLP projector operates is widely different and even the final product of how an image comes out is not the same. With DLP, white light from the lamp is processed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of forming an image creates a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to create the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eye will then put together each coloured element of the image into a single total image. Using LCD projectors, all colours are available all the time to offer high brightness and spectacular colour accuracy. In DLP, only one colour is available at once, resulting in lower colour brightness and accuracy. Some designers have added a white segment in the colour wheel to improve brightness overall, but this goes and detracts from colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and ergo must be superior. 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 system is capable of. DLP projectors do offer high contrast specifications when compared to many LCD projectors. At one glance, this must be a benefit, however, in the real world, the true black level is determined by the ambient light in the room where the projector is being utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to bring to life requires moving images, DLP projection technology can also create image imperfections, or ‘artifacts’. The most typical artifact that a DLP projector forms with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change up between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because all colours are processed at the same time. DLP designers have created 3DLP solutions using 3 chips to answer the colour break up issue, but the expense of these projectors make them almost impossible for many businesses and consumers.
Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and remember how the various colours of light refract different amounts when projected through the same lens. The downside 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 obviously not the same and refract light differently. Often with a DLP projector, a spill of yellow colour will show above and some blue will show below something as simple as a single black line. During manufacturing LCD projectors can be fixed to remove these effects on the projected image, as each colour is refracted on separate LCD panels.
The one actual buy point (excluding price) with picking a DLP projector is its smaller total size and weight. However, this is only relevant to portability and has to be traded off against the image benefits of LCD projectors. If resulting picture quality is important to you, then the choice is a no-brainer. Go for an LCD projector! LCD projectors will constantly make bright, colourful images with fewer image imperfections. If you need to ask more about LCD technology in more detail, check out this fabulous resource website: Explore 3LCD. If you have any more questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager with 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.
