19 Jul 10 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: would I take an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most common projector imaging technologies. With so many business brands and different types available, it can be challenging for consumers to make a decision between both technologies. It comes down to the fact that LCD projectors provide far better image quality and colour accuracy. The following article will explain why DLP projectors struggle with bringing up an equal grade of image quality.
Think of a set of blinds in your house for your bedroom window. By a twist of a rod you can have the shutters open or closed, depending on if you want to let light in or not. And such is exactly how an LCD projector operates. Each pixel operates like an individual 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 pros 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 switches on to when the image reaches your screen is vitally important in regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by separating 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 send the projector image. An important point to know about LCD projectors is that all three colours are delivered onto your wall all at the same time. The way a DLP projector operates is very 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 turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of projecting 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 form 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 combine each coloured element of the image into a single full image. From LCD projectors, all colours are available all the time to offer top 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 designers have placed a white segment for the colour wheel to improve brightness overall, but this further degrades colour accuracy.
I see in forums all the time that DLP provides a higher contrast ratio and ergo must be better. For those who are unsure, 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 compared to most LCD projectors. At first glance, this appears to be a plus, however, in real life, the true black level is determined by the ambient light in the room where the projector is utilised. Do not be fooled 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 create image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector forms with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change between the time red, blue and green colours are shone. LCD projectors do not have this downside because all the colours are projected at the same time. DLP developers have formed 3DLP solutions using 3 chips to answer the colour break up error, but the price tag of these projectors make them almost impossible 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 they taught you how various colours of light refract different amounts when directed through the same lens. The downfall 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 differently. Often with a DLP projector, some yellow colour will come through above and an extra blue will come up below an image of something as simple as a lone black line. In building LCD projectors can be set to take away these effects on the projected image, as each colour is processed on isolated LCD panels.
The one real buy point (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to mobility and cannot be traded off against the image benefits of LCD projectors. If the result of the picture quality is crucial to you, then the answer is no-brainer. Choose an LCD projector! LCD projectors will always show bright, colourful images with fewer image imperfections. If you need to learn more about LCD technology in more detail, have a gander at this fabulous resource website: Explore 3LCD. If you have any additional questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s premier online shop 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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