Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question asked when purchasing a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many different brands and types available, it can be challenging for the buyer to make a decision between the two technologies. The simple fact of the matter is that LCD projectors offer far superior image quality and colour accuracy. The article below will tell you why DLP projectors struggle with projecting a similar standard of image quality.
Visualise a set of blinds in your household on 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 this is exactly how an LCD projector behaves. Each pixel works like a unique shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is made up of millions of microscopic mirrors or ‘pixel elements’ as the experts 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 switches on to when the picture reaches your screen is vitally important with 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 send the coloured light to 3 stand alone LCD panels. The 3 LCD panels create the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to form the projector image. A point to know about LCD projectors is that all three colours are delivered onto your projected surface simultaneously. The way a DLP projector functions is very different and even how an image looks 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 projecting 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 displayed in sequence on the screen, one colour at a time. The viewer’s eyes will then pull together each coloured element of the image into the full image. In LCD projectors, all colours are available all the time to offer the highest brightness and superb colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some DLP designers have included a white segment in the colour wheel to improve overall brightness, but this also detracts from colour accuracy.
I find in forums all the time that DLP offers a higher contrast ratio and as such must be better. 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 technology is able to produce. DLP projectors do possess high contrast specifications compared to many LCD projectors. At first glance, this can seem to be a benefit, however, in the real world, the true black level is determined by the ambient light in the room while the projector is utilised. Do not be fooled by contrast specifications on websites and in brochures.
When the content you want to bring to life requires moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector creates with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images keep changing between the time red, blue and green colours are projected. LCD projectors do not have this characteristic because all the colours are projected simultaneously. DLP builders have come up with 3DLP solutions using 3 chips to resolve the colour break up artifacts, but the expense of these projectors make them not practical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they make up for the refractive qualities of light. Think back to high school science, and remember when they taught you how different colours of light refract varied amounts when projected through the same lens. The problem 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 not the same and refract light in different ways. Most of the time with a DLP projector, an extra yellow colour will show above and a spill of blue will show below an image of something as simple as a straight black line. In building LCD projectors can be fixed to reduce these effects on the projected image, because each colour is projected on a separate LCD panels.
The sole actual plus (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant for transporting the device and cannot be traded off against the image plusses of LCD projectors. If resulting picture quality is vital to you, then the choice is no-brainer. Go for an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image imperfections. If you desire to ask more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any persisting questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online shop for projectors. Brisbane-based, Projector Central has serviced Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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