Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question asked when looking for a new projector for the home, office, or classroom is: will I get an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and different types available, it can be challenging for the buyer to make a decision between those technologies. Ultimately LCD projectors give far superior image quality and colour accuracy. The following article will explain why DLP projectors struggle with projecting the same level of image quality.
Imagine a set of blinds in your room over your bedroom window. With the twist of a rod you can turn the shutters open or closed, according to if you want to let light in or not. And that is exactly how an LCD projector operates. Each pixel functions like a unique shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is made up 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 is switched on to when the image reaches your screen is ultimately significant in regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting it into red, blue and green components, by three mirrors which direct the coloured light to 3 different LCD panels. The 3 LCD panels create the elements of the image by shining each pixel on and off. The pixels are then combined in a glass prism to form the projector image. Something important to realise about LCD projectors is that all three colours are delivered onto your screen at once. The way a DLP projector works is totally different and even the produced image shows up is not the same. With DLP, white light from the lamp is processed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This approach to making an image casts a sequence of red, blue and green light. The millions of micro mirrors mentioned above reflect the coloured light on the pixels to create the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eyes will then draw each coloured element of the image into a complete image. With LCD projectors, all colours are available all the time to offer the highest brightness and spectacular colour accuracy. In DLP, only one colour is available at a time, causing lower colour brightness and accuracy. Some designers have put a white segment into the colour wheel to improve brightness overall, but this then damages colour accuracy.
I see in forums all the time that DLP provides a higher contrast ratio and thus must be superior quality. 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 projector is capable of producing. DLP projectors do provide high contrast specifications when compared to most LCD projectors. Initially, this appears to be a benefit, however, in real life, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you want to bring to life has moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most common artifact that a DLP projector forms with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change position between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because all the colours are projected simultaneously. DLP builders have developed 3DLP solutions using 3 chips to resolve the colour break up issue, but the price tag of these projectors make them hardly practical for many businesses and consumers.
Another differentiation between LCD and DLP is how they match the balance for the refractive qualities of light. Take yourself back to high school science, and remember how the different colours of light refract different amounts when directed through the same lens. The disadvantage 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. Usually with a DLP projector, a spill of yellow colour will come up above and some extra blue will come through below something as simple as a single black line. In manufacturing LCD projectors can be fixed to take away these effects on the projected image, as each colour is projected on isolated LCD panels.
The one actual advantage (excluding price) with taking a DLP projector is its overall smaller size and weight. However, this is only relevant for mobility and cannot be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is vital to you, then the decision is a no-brainer. Take an LCD projector! LCD projectors will always produce bright, colourful images with fewer image imperfections. If you desire to learn more about LCD technology in more detail, check out this spectacular 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 of Projector Central, Australia’s leading online store for projectors. Brisbane based, Projector Central has been servicing Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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