The most typical question asked when acquiring a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short 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 consumers to decide between the two technologies. The fact is that LCD projectors have superior image quality and colour accuracy. The article below tells you why DLP projectors struggle with projecting the same rate of image quality.
Imagine a set of blinds in your house covering your bedroom window. By twisting a rod you can turn the shutters open or closed, according to if you want to let light in or not. That is exactly how an LCD projector behaves. Each pixel functions like its own 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 the point at which the projector turns 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 transfer the coloured light to 3 stand alone LCD panels. The 3 LCD panels form the elements of the image by turning each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. An important point to understad about LCD projectors is that all three colours are projected onto your screen simultaneously. The way a DLP projector functions is very different and even the final product of how an image appears is not the same. With DLP, white light from the lamp is projected through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image requires a sequence of red, blue and green light. The millions of micro mirrors as 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 eyes will then combine each coloured element of the image into the full image. Using LCD projectors, all colours are available all the time to deliver the top level of brightness and great 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 included a white segment in the colour wheel to improve overall brightness, but this goes and damages colour accuracy.
I read in forums all the time that DLP gives a higher contrast ratio and thus must be better. 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 projector is able to produce. DLP projectors do possess high contrast specifications when compared to many LCD projectors. At first glance, this must be a plus, however, in reality, the true black level is determined by the ambient light in the room while the projector is in use. Do not be fooled by contrast specifications on websites and in brochures.
When the content you want to project has moving images, DLP projection technology can also have image imperfections, 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 projected. LCD projectors do not have this disadvantage because all colours are delivered at once. DLP manufacturers have come up with 3DLP solutions using 3 chips to fix the colour break up error, but the cost of these projectors make them hardly practical for most businesses and consumers.
Another differentiation 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 the various colours of light refract different amounts when directed through the same lens. The disadvantage with DLP projectors is that they take the one same panel with the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light at different levels. Often with a DLP projector, a spill of yellow colour will show above and an extra blue will be projected below something as simple as a single black line. In manufacturing LCD projectors can be adjusted to take away these effects on the projected image, as each colour is projected on a separate LCD panels.
The one veritable buy point (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to transport and has to be traded off against the image advantages of LCD projectors. If resulting picture quality is important to you, then the decision is a no-brainer. Go with an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image blips. If you wish to learn more about LCD technology in more detail, have a gander at this spectacular 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 for Projector Central, Australia’s number one online provider for projectors. Brisbane-based, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
