Projectors: LCD Verses DLP (The downfall of DLP technology)
The most typical question customers ask when acquiring a new projector for the home, office, or classroom is: should I take an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many different brands and types available, it can be challenging for customers to make a choice between those technologies. The fact is that LCD projectors have far superior image quality and colour accuracy. The following article will explain why DLP projectors struggle with bringing up a comparable grade of image quality.
Visualise a set of blinds in your room on your bedroom window. By twisting 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 works. Each pixel operates like an individual shutter on a set of blinds to either shine 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 functions to either reflect light or block it.
How the light source is processed from when the projector turns on to when the content reaches your screen is vitally significant 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 individual LCD panels. The 3 LCD panels cast the elements of the image by processing each pixel on and off. The pixels are then meshed in a glass prism to deliver the projector image. A point to know about LCD projectors is that all three colours are projected onto your screen at the same time. The way a DLP projector functions is widely different and even the way an image looks 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 creates a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to construct the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s vision will then combine each coloured element of the image into the single whole image. With LCD projectors, all colours are available all the time to create the highest 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 DLP designers have placed a white segment into the colour wheel to improve brightness generally, but this also lessens colour accuracy.
I read in forums all the time that DLP offers a higher contrast ratio and as such must be better 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 able to produce. DLP projectors do provide high contrast specifications when compared to the majority of LCD projectors. At a glance, this seems to be a plus, however, in truth, the true black level is determined by the ambient light in the room in which the projector is being utilised. Do not be tricked by contrast specifications on websites and in brochures.
When the content you are trying to see includes moving images, DLP projection technology also has image imperfections, or ‘artifacts’. The most common artifact that a DLP projector shows with moving images is colour break up. Colour break up is unavoidable in DLP systems because moving images change up between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because all colours are projected simultaneously. DLP developers have created 3DLP solutions using 3 chips to answer the colour break up error, but the price of these projectors make them hardly practical for the majority of businesses and consumers.
Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Think back to high school science, and recall when they taught you how the various colours of light refract various amounts when shone through the same lens. The downfall with DLP projectors is that they have the one same panel with 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 extra yellow colour will be projected above and some blue will come through below an image of something as simple as a lone black line. In building LCD projectors can be adapted to take away these effects on the projected image, as each colour is refracted on separate LCD panels.
The isolated actual buy point (excluding price) with choosing a DLP projector is its overall smaller size and weight. However, this is only relevant with regard to mobility and cannot be traded off against the image plusses of LCD projectors. If resulting picture quality is important to you, then the solution is simple. Take an LCD projector! LCD projectors will always make bright, colourful images with fewer image mistakes. If you desire to learn more about LCD technology in more detail, have a look at this tremendous resource website: Explore 3LCD. If you have any additional questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s number one online shop for projectors. Brisbane based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.