Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when looking for a new projector for the home, office, or classroom is: do I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two top projector imaging technologies. With so many brands and different types available, it can be confusing for consumers to pick between the two technologies. The fact is that LCD projectors give far superior image quality and colour accuracy. The following article will explain why DLP projectors struggle with projecting a comparable standard of image quality.
Imagine a set of blinds in your household on your bedroom window. By pulling on a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. And that is exactly how an LCD projector functions. Each pixel functions like its own shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is formed 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 point at which the projector switches on to when the image reaches your screen is vitally important for image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by dividing it into red, blue and green components, by three mirrors which send the coloured light to 3 stand alone LCD panels. The 3 LCD panels cast the elements of the image by switching each pixel on and off. The pixels are then meshed in a glass prism to deliver the projector image. Something important to remember about LCD projectors is that all three colours are sent onto your screen simultaneously. The way a DLP projector operates is widely different and even the final product of how an image looks 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 creating an image forms a sequence of red, blue and green light. The millions of micro mirrors as described above reflect the coloured light on the pixels to form the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eyes will then draw each coloured element of the image into the single total image. With LCD projectors, all colours are available all the time to offer the top level of brightness and spectacular colour accuracy. In DLP, just one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some DLP designers have placed a white segment into the colour wheel to improve brightness generally, 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 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 projector is capable of. DLP projectors do offer high contrast specifications as compared to the majority of LCD projectors. At one glance, this can seem 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 used. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you wish to bring to life requires moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most typical artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because every colour is processed with the others. DLP designers have created 3DLP solutions using 3 chips to solve the colour break up issue, but the cost of these projectors make them impractical for many businesses and consumers.
Another variance between LCD and DLP is how they balance for the refractive qualities of light. Think back to high school science, and remember how various colours of light refract varied amounts when passing through the same lens. The downside with DLP projectors is that they utilise the one same panel with the same lens to project Red, Blue and Green. All 3 colours are obviously different and refract light in a different way. Often with a DLP projector, some yellow colour will be projected above and a superfluous blue will come through below an image containing something as simple as a lone black line. While being built LCD projectors can be fixed to take away these effects on the projected image, because each colour is processed on its own LCD panels.
The sole veritable benefit (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant for transport and cannot be traded off against the image advantages of LCD projectors. If resulting picture quality is vital to you, then the decision is a no-brainer. Go for an LCD projector! LCD projectors will definitely show 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, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s leading online provider for projectors. Based in Brisbane, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.