The common question that is asked when looking for a new projector for the home, office, or classroom is: will I buy an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and models available, it can be challenging for clients to choose between the two technologies. It comes down to the fact that LCD projectors have far superior image quality and colour accuracy. The article below explains why DLP projectors struggle with bringing up a similar standard of image quality.
It’s like a set of blinds in your household 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. That is exactly how an LCD projector behaves. Each pixel functions like a single shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as the pros like to call them. Each pixel element functions 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 image reaches your screen is extremely important with regard to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by dividing it into red, blue and green components, by three mirrors which direct the coloured light to 3 individual LCD panels. The 3 LCD panels make the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to send the projector image. Something to understad about LCD projectors is that all three colours are projected onto your projector screen at the same time. The way a DLP projector functions is vastly different and even the final product of how an image shows up 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 forming 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 create the image elements. The elements of the image are sent 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 complete image. With LCD projectors, all colours are available all the time to create the best brightness and fantastic colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some manufacturers have included a white segment into the colour wheel to improve brightness overall, but this goes and damages colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and ergo must be better. 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 machine is capable of producing. DLP projectors do provide high contrast specifications when compared to most LCD projectors. At one glance, this must 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 hoodwinked by contrast specifications on websites and in brochures.
When the content you want to see includes moving images, DLP projection technology can also create image errors, 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 displayed. LCD projectors do not have this problem because every colour is sent simultaneously. DLP manufacturers have created 3DLP solutions using 3 chips to answer the colour break up problem, but the expense of these projectors make them impractical for many businesses and consumers.
Another variance between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and they taught you how different colours of light refract various amounts when directed through the same lens. The downside with DLP projectors is that they take the one same panel for the same lens to project Red, Blue and Green. All 3 colours are different and refract light at different levels. Often with a DLP projector, some yellow colour will come up above and an extra blue will show below something as simple as a single black line. In building LCD projectors can be adapted to take away these effects on the projected image, as each colour is processed on isolated LCD panels.
The only true plus (excluding price) with buying a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to mobility and cannot be traded off against the image advantages of LCD projectors. If resulting picture quality is vital to you, then the decision is easy. Choose an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image blips. If you want to ask more about LCD technology in more detail, check out this fabulous resource website: Explore 3LCD. If you have any persisting questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s premier online provider for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
