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

The typical question heard when purchasing a new projector for the home, office, or classroom is: should I buy an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many company brands and different types available, it can be challenging for clients to decide between both technologies. The fact is that LCD projectors have superior image quality and colour accuracy. The article below tells you why DLP projectors struggle with creating an equal rate of image quality.

Think of a set of blinds in your home on your bedroom window. By twisting a rod you can have the shutters open or closed, according to if you want to let light in or not. Such is exactly how an LCD projector operates. Each pixel operates like an individual shutter on a set of blinds to either send light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as the professionals like to call them. Each pixel element works to either reflect light or block it.

How the light source is processed from when the projector turns on to when the picture reaches your screen is absolutely significant for image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which project the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by switching each pixel on and off. The pixels are then meshed in a glass prism to deliver the projector image. An important point to understad about LCD projectors is that all three colours are delivered onto your projector screen all at once. The way a DLP projector works is totally different and even the final product of how an image looks is not the same. With DLP, white light from the lamp is directed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to creating an image forms a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to produce the image elements. The elements of the image are sent in sequence on the screen, one colour at a time. The viewer’s eyes will then put together each coloured element of the image into a whole image. With LCD projectors, all colours are available all the time to form the top level of brightness and superb colour accuracy. In DLP, only one colour is available at a time, and so causing lower colour brightness and accuracy. Some designers have added a white segment for the colour wheel to improve overall brightness, but this goes and detracts from colour accuracy.

I see in forums all the time that DLP has a higher contrast ratio and as such must be superior. 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 compared to many LCD projectors. At first glance, this seems to be an advantage, however, in the real world, the true black level is determined by the ambient light in the room where the projector is being used. Do not be duped by contrast specifications on websites and in brochures.

When the content you want to project requires moving images, DLP projection technology also creates image errors, or ‘artifacts’. The most often seen 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 between the time red, blue and green colours are projected. LCD projectors do not have this problem because every colour is projected simultaneously. DLP builders have created 3DLP solutions using 3 chips to answer the colour break up problem, 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 match the balance for the refractive qualities of light. Jump back to high school science, and recall when they taught you how various colours of light refract differing amounts when directed through the same lens. The disadvantage with DLP projectors is that they use the one same panel and the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in different ways. Most of the time with a DLP projector, a superfluous yellow colour will come through above and some extra blue will appear below an image of something as simple as a straight black line. In building LCD projectors can be set to take away these effects on the projected image, because each colour is processed on a separate LCD panels.

The only veritable buy point (excluding price) with choosing a DLP projector is its smaller total size and weight. However, this is only relevant to transporting the device and cannot be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is important to you, then the solution is a no-brainer. Go for an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image mistakes. If you wish to find out more about LCD technology in more detail, have a gander at this fantastic 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 retailer for projectors. Brisbane-based, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.