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

The most common question asked when acquiring 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, which stands for ‘digital light processing’ are the two top projector imaging technologies. With so many different brands and different models available, it can be challenging for customers to make a choice between those technologies. It comes down to the fact that LCD projectors offer superior image quality and colour accuracy. The next part of this article tells you why DLP projectors struggle with bringing up a comparable standard of image quality.

Visualise a set of blinds in your home on 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. And such is exactly how an LCD projector operates. Each pixel operates like a single shutter on a set of blinds to either shine 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 operates to either reflect light or block it.

How the light source is processed from the point when the projector is turned on to when the content reaches your screen is extremely important in regard to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 individual LCD panels. The 3 LCD panels create the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. Something to remember about LCD projectors is that all three colours are delivered onto your projector screen at the same time. The way a DLP projector operates is very different and even the final product of how an image looks is not the same. With DLP, white light from the lamp is sent through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image casts a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to form the image elements. The elements of the image are sent 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 the single full image. Using LCD projectors, all colours are available all the time to form the highest brightness and fantastic colour accuracy. In DLP, only one colour is available at any given time, causing lower colour brightness and accuracy. Some designers have put a white segment into the colour wheel to improve all over brightness, but this then lessens colour accuracy.

I see in forums all the time that DLP has a higher contrast ratio and therefore must be superior quality. For those 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 technology is capable of producing. DLP projectors do have high contrast specifications in comparison to most LCD projectors. At a glance, this seems to be a plus, however, in the real world, the true black level is determined by the ambient light in the room where the projector is being utilised. Do not be duped by contrast specifications on websites and in brochures.

When the content you plan to bring to life requires moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most often seen artifact that a DLP projector shows with moving images is colour break up. Colour break up is unavoidable 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 disadvantage because all the colours are delivered simultaneously. DLP developers have created 3DLP solutions using 3 chips to fix the colour break up error, but the price tag of these projectors make them impractical for the majority of businesses and consumers.

Another difference between LCD and DLP is how they compensate for the refractive qualities of light. Remember back to high school science, and recall how different colours of light refract various amounts when passing through the same lens. The problem with DLP projectors is that they have 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. Generally with a DLP projector, some yellow colour will show above and some extra blue will come through below something as simple as a straight black line. During manufacturing LCD projectors can be adjusted to remove these effects on the projected image, as each colour is refracted on a separate LCD panels.

The one true benefit (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to transport and needs to be traded off against the image plusses of LCD projectors. If overall picture quality is vital to you, then the decision is simple. Go with an LCD projector! LCD projectors will always produce bright, colourful images with fewer image imperfections. If you need to ask more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any persisting questions, go to 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. Based in Brisbane, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.