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: would I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many company brands and types available, it can be confusing for the buyer to decide between both technologies. The fact is that LCD projectors give superior image quality and colour accuracy. The article below will tell you why DLP projectors struggle with creating an equal level of image quality.
Visualise a set of blinds in your home on your bedroom window. By twisting a rod you can have the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector works. Each pixel functions like a unique shutter on a set of blinds to either send light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as pros like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from when the projector turns on to when the picture reaches your screen is extremely significant with 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 direct the coloured light to 3 separate LCD panels. The 3 LCD panels form the elements of the image by processing each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. A significant point to remember about LCD projectors is that all three colours are delivered onto your projector screen simultaneously. The way a DLP projector functions is totally different and even the way an image shows up is not the same. With DLP, white light from the lamp is directed 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 mentioned 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 draw each coloured element of the image into the single whole image. In LCD projectors, all colours are available all the time to deliver the top level of brightness and superb colour accuracy. In DLP, only one colour is available at any given time, and so causing lower colour brightness and accuracy. Some developers have added a white segment for the colour wheel to improve overall brightness, but this goes and lessens colour accuracy.
I hear in forums all the time that DLP has a higher contrast ratio and as such must be superior. For those 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. DLP projectors do have high contrast specifications in comparison to most LCD projectors. At one glance, this appears to be an advantage, however, in reality, the true black level is determined by the ambient light in the room where the projector is being used. Do not be duped by contrast specifications on websites and in brochures.
When the content you wish to bring to life needs moving images, DLP projection technology also has image errors, or ‘artifacts’. The most typical artifact that a DLP projector displays with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this disadvantage because the colours are delivered with the others. DLP manufacturers have created 3DLP solutions using 3 chips to fix the colour break up problem, but the cost of these projectors make them not practical for many businesses and consumers.
Another point of difference between LCD and DLP is how they balance for the refractive qualities of light. Take yourself back to high school science, and recall when they taught you how various colours of light refract varied amounts when projected through the same lens. The disadvantage 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 in different ways. Most of the time with a DLP projector, some yellow colour will appear above and a spill of blue will show below an image containing something as simple as a single black line. In manufacturing LCD projectors can be set to take away these effects on the projected image, because each colour is projected on a separate LCD panels.
The one true buy point (excluding price) with buying a DLP projector is its overall smaller size and weight. However, this is only relevant in regard to mobility and must be traded off against the image superiority of LCD projectors. If the outcome of the picture quality is crucial to you, then the choice is easy. Go with an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image imperfections. If you desire to ask more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any further questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s top online provider for projectors. Brisbane-based, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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