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

The most typical question that is asked when acquiring a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many different brands and types available, it can be difficult for the buyer to pick between both technologies. The simple fact of the matter is that LCD projectors give superior image quality and colour accuracy. The next part of this article explains why DLP projectors struggle with projecting an equal level of image quality.

Think of a set of blinds in your household covering your bedroom window. With the twist of a rod you can turn the shutters open or closed, depending on if you want to let light in or not. Such is exactly how an LCD projector functions. 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 formed of millions of microscopic mirrors or ‘pixel elements’ as 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 switches on to when the picture reaches your screen is vitally important for image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by separating it into red, blue and green components, by three mirrors which project the coloured light to 3 stand alone LCD panels. The 3 LCD panels make the elements of the image by switching each pixel on and off. The pixels are then simultaneously processed in a glass prism to create the projector image. An important point to know about LCD projectors is that all three colours are directed onto your projected surface all at the same time. The way a DLP projector runs is widely 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 approach to forming an image creates a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to construct 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 combine each coloured element of the image into a single whole image. In LCD projectors, all colours are available all the time to offer the highest brightness and spectacular colour accuracy. In DLP, just one colour is available at once, and so causing lower colour brightness and accuracy. Some designers have put a white segment into the colour wheel to improve all over brightness, but this goes and damages colour accuracy.

I read in forums all the time that DLP has a higher contrast ratio and as such must be better. For those who are unsure, 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 technology is capable of producing. DLP projectors do provide high contrast specifications 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 used. Do not be fooled by contrast specifications on websites and in brochures.

When the content you are trying to bring to life requires moving images, DLP projection technology can also create image errors, or ‘artifacts’. The most often seen artifact that a DLP projector shows with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change up between the time red, blue and green colours are pulled up. LCD projectors do not have this downside because every colour is sent simultaneously. DLP developers have formed 3DLP solutions using 3 chips to answer the colour break up problem, but the price tag of these projectors make them almost impossible for most businesses and consumers.

Another point of difference between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and remember how various colours of light refract varied amounts when directed through the same lens. The problem 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. Most of the time with a DLP projector, some extra yellow colour will come up above and a spill of blue will be projected below an image as simple as a straight black line. While being built LCD projectors can be set to reduce these effects on the projected image, because each colour is processed on its own LCD panels.

The only actual buy point (excluding price) with choosing a DLP projector is its smaller size and weight. However, this is only relevant in regard to transport and has to be traded off against the image superiority of LCD projectors. If resulting picture quality is crucial to you, then the decision is easy. Go for an LCD projector! LCD projectors will definitely produce bright, colourful images with fewer image errors. If you wish to learn more about LCD technology in more detail, have a gander at this fantastic resource website: Explore 3LCD. If you have any additional questions, jump onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager with Projector Central, Australia’s top online shop for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.