Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question that is asked when purchasing a new projector for the home, office, or classroom is: do I purchase 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 brands and types available, it can be difficult for consumers to make a decision between the two technologies. The simple fact of the matter is that LCD projectors provide superior image quality and colour accuracy. The article below will tell you why DLP projectors struggle with bringing up the same standard of image quality.
Imagine a set of blinds in your house on your bedroom window. By pulling on a rod you can have the shutters open or closed, depending on if you want to let light in or not. That 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 formed of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element functions 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 extremely significant to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by dividing it into red, blue and green components, by three mirrors which transfer the coloured light to 3 stand alone LCD panels. The 3 LCD panels form the elements of the image by turning each pixel on and off. The pixels are then meshed in a glass prism to create the projector image. A point to understad about LCD projectors is that all three colours are sent onto your projector screen at the same time. The way a DLP projector operates is widely different and even the produced image shows up 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 approach to creating an image requires a sequence of red, blue and green light. The millions of micro mirrors mentioned 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 eyes will then draw each coloured element of the image into a complete image. With LCD projectors, all colours are available all the time to create the top level of brightness and great colour accuracy. In DLP, just one colour is available at any given time, and so causing lower colour brightness and accuracy. Some DLP developers have placed a white segment for the colour wheel to improve brightness generally, but this then detracts from colour accuracy.
I hear in forums all the time that DLP gives a higher contrast ratio and ergo must be better. 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 system is capable of. DLP projectors do provide high contrast specifications when compared to the majority of LCD projectors. At first glance, this seems to be a plus, however, in real life, the true black level is determined by the ambient light in the room while the projector is being utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you want to see has moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most typical 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 between the time red, blue and green colours are projected. LCD projectors do not have this characteristic because all the colours are processed with the others. DLP builders have developed 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the cost of these projectors make them hardly practical for the large part of businesses and consumers.
Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and remember when they taught you how the various colours of light refract different amounts when projected through the same lens. The downfall 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 not the same and refract light in a different way. Usually with a DLP projector, some yellow colour will show above and a superfluous blue will come up below something as simple as a lone black line. While being built LCD projectors can be adjusted to reduce these effects on the projected image, as each colour is projected on a separate LCD panels.
The one real benefit (excluding price) with picking a DLP projector is its overall smaller size and weight. However, this is only relevant for mobility and has to be traded off against the image benefits of LCD projectors. If the result of the picture quality is crucial to you, then the choice is no-brainer. Choose an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you need to ask more about LCD technology in more detail, have a look at this tremendous resource website: Explore 3LCD. If you have any more questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s leading online retailer for projectors. Based in Brisbane, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
