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

The most common question customers ask when acquiring a new projector for the home, office, or classroom is: do I take an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many brands and types available, it can be overwhelming for clients to choose between these technologies. It comes down to the fact that LCD projectors give far better image quality and colour accuracy. The next part of this article tells you why DLP projectors struggle with reproducing a comparable rate of image quality.

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

How the light source is processed from the time the projector is switched on to when the image reaches your screen is ultimately significant for image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels create the elements of the image by shining each pixel on and off. The pixels are then projected in a glass prism to send the projector image. An important point to know about LCD projectors is that all three colours are projected onto your screen at once. The way a DLP projector operates is widely different and even the produced image comes out is not the same. With DLP, white light from the lamp is projected through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of making 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 eye will then pull together each coloured element of the image into the total image. From LCD projectors, all colours are available all the time to form the highest brightness and spectacular colour accuracy. In DLP, just one colour is available at any given time, and so causing lower colour brightness and accuracy. Some DLP manufacturers have placed a white segment for the colour wheel to improve brightness overall, but this then damages colour accuracy.

I see in forums all the time that DLP has a higher contrast ratio and as such must be superior quality. 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 able to produce. DLP projectors do possess high contrast specifications in comparison to most LCD projectors. At one glance, this seems to be an advantage, however, in reality, the true black level is determined by the ambient light in the room where the projector is used. Do not be fooled by contrast specifications on websites and in brochures.

When the content you want to project requires moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most often seen artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this characteristic because every colour is delivered at once. DLP manufacturers have developed 3DLP solutions using 3 chips to solve the colour break up issue, but the expense of these projectors make them almost impossible for most businesses and consumers.

Another variance between LCD and DLP is how they balance for the refractive qualities of light. Jump back to high school science, and remember how the different colours of light refract differing amounts when directed through the same lens. The problem with DLP projectors is that they take the one same panel and 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 show above and a superfluous blue will appear below something as simple as a single black line. While being built LCD projectors can be adjusted to reduce these effects on the projected image, because each colour is projected on its own LCD panels.

The sole true benefit (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant for transport and needs to be traded off against the image plusses of LCD projectors. If overall picture quality is important to you, then the answer is easy. Choose an LCD projector! LCD projectors will definitely make bright, colourful images with fewer image blips. If you need to know more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any more questions, go to Projector Central and send me an email.

Jonathan King is the sales and marketing manager with Projector Central, Australia’s number one online provider 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.