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

The most common question that is asked when looking for a new projector for the home, office, or classroom is: would I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and models available, it can be challenging for consumers to decide between both technologies. The fact is that LCD projectors provide superior image quality and colour accuracy. The article below explains why DLP projectors struggle with reproducing an equal grade of image quality.

Visualise a set of blinds in your home covering your bedroom window. By a twist of a rod you can have the shutters open or closed, depending on if you want to let light in or not. And that is exactly how an LCD projector works. Each pixel works like an individual 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 the professionals like to call them. Each pixel element functions to either reflect light or block it.

How the light source is processed from when the projector is turned on to when the content reaches your screen is ultimately important to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 different LCD panels. The 3 LCD panels create the elements of the image by switching each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. An important point to remember about LCD projectors is that all three colours are sent onto your projected surface all at once. The way a DLP projector operates is very different and even how an image appears is not the same. With DLP, white light from the lamp is sent through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of creating 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 vision will then pull together each coloured element of the image into a total image. With LCD projectors, all colours are available all the time to deliver the highest brightness and spectacular colour accuracy. In DLP, just one colour is available at a time, causing lower colour brightness and accuracy. Some designers have placed a white segment in the colour wheel to improve brightness overall, but this then detracts from colour accuracy.

I read in forums all the time that DLP offers a higher contrast ratio and thus must be superior. For those who don’t 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 machine is capable of producing. DLP projectors do have high contrast specifications when compared to many LCD projectors. At a glance, this seems to be a plus, however, in truth, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be duped by contrast specifications on websites and in brochures.

When the content you wish to see needs moving images, DLP projection technology also creates image errors, or ‘artifacts’. The most common artifact that a DLP projector forms with moving images is colour break up. Colour break up is inherent in DLP systems because moving images keep changing between the time red, blue and green colours are pulled up. LCD projectors do not have this downside because the colours are processed with the others. DLP builders have formed 3DLP solutions using 3 chips to resolve the colour break up error, but the cost of these projectors make them almost impossible for the large part of businesses and consumers.

Another point of difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and remember how different colours of light refract varied amounts when shone through the same lens. The downside with DLP projectors is that they utilise 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 in a different way. Often with a DLP projector, some yellow colour will appear above and some extra blue will come through below an image of something as simple as a single black line. During manufacturing LCD projectors can be set to take away these effects on the projected image, because each colour is directed on separate LCD panels.

The sole true buy point (excluding price) with going with a DLP projector is its smaller total size and weight. However, this is only relevant to transport and has to be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is important to you, then the solution is no-brainer. Go with an LCD projector! LCD projectors will definitely make bright, colourful images with fewer image mistakes. If you want to know more about LCD technology in more detail, check out this spectacular 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 with Projector Central, Australia’s leading online store for projectors. Based in Brisbane, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.