Projectors: LCD Verses DLP (The downfall of DLP technology)

The most common question heard when purchasing a new projector for the home, office, or classroom is: would I get an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most popular projector imaging technologies. With so many different brands and different models available, it can be challenging for consumers to decide between the two technologies. The fact is that LCD projectors have better image quality and colour accuracy. The next part of this article tells you why DLP projectors struggle with bringing up a comparable grade of image quality.

It’s like a set of blinds in your house over your bedroom window. By pulling on a rod you can turn the shutters open or closed, depending on if you want to let light in or not. This is exactly how an LCD projector functions. Each pixel operates like a unique shutter on a set of blinds to either allow 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 functions 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 image reaches your screen is absolutely significant to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by cutting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 different LCD panels. The 3 LCD panels form 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. Something important to realise about LCD projectors is that all three colours are projected onto your screen at once. The way a DLP projector functions 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 directed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of creating an image casts a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to form 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 put together each coloured element of the image into the whole image. Using LCD projectors, all colours are available all the time to offer high brightness and spectacular colour accuracy. In DLP, just one colour is available at once, causing lower colour brightness and accuracy. Some DLP developers have placed a white segment into the colour wheel to improve overall brightness, but this goes and degrades colour accuracy.

I find in forums all the time that DLP gives a higher contrast ratio and therefore must be better. For those who are unaware, 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 as compared to many LCD projectors. At first glance, this appears 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 hoodwinked by contrast specifications on websites and in brochures.

When the content you plan to view has moving images, DLP projection technology also has image marks, or ‘artifacts’. The most common artifact that a DLP projector displays with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change position between the time red, blue and green colours are pulled up. LCD projectors do not have this downside because all the colours are sent with the others. DLP developers have created 3DLP solutions using 3 chips to resolve the colour break up error, but the price of these projectors make them hardly practical for the large part of businesses and consumers.

Another point of difference between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and remember when they taught you how the various colours of light refract different amounts when shone through the same lens. The downfall with DLP projectors is that they utilise 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. Often with a DLP projector, an extra yellow colour will appear above and some blue will show below something as simple as a lone black line. During manufacturing LCD projectors can be set to remove these effects on the projected image, as each colour is directed on its own LCD panels.

The isolated actual plus (excluding price) with deciding on a DLP projector is its overall smaller 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 the outcome of the picture quality is crucial to you, then the answer is simple. Go for an LCD projector! LCD projectors will always show bright, colourful images with fewer image errors. If you need to find out more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any additional questions, visit Projector Central and send me an email.

Jonathan King is the sales and marketing manager for Projector Central, Australia’s premier online retailer for projectors. Based in Brisbane, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.