The typical question that is asked when buying a new projector for the home, office, or classroom is: will I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, which stands for ‘digital light processing’ are the two most common projector imaging technologies. With so many different brands and different models available, it can be difficult for clients to make a choice between the two technologies. Ultimately LCD projectors offer far superior image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with bringing up a comparable grade of image quality.
Imagine a set of blinds in your home over your bedroom window. By a twist of a rod you can make the shutters open or closed, depending on if you want to let light in or not. And this is exactly how an LCD projector behaves. Each pixel works like its own shutter on a set of blinds to either allow light through or to block it. DLP on the other hand is formed of millions of microscopic mirrors or ‘pixel elements’ as the pros like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from the point when the projector switches on to when the content reaches your screen is absolutely significant with regard to image quality, brightness and colour accuracy. LCD projectors process white light from the lamp by splitting it into red, blue and green components, by three mirrors which transfer the coloured light to 3 separate 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 deliver the projector image. Something important to realise about LCD projectors is that all three colours are projected onto your projected surface simultaneously. The way a DLP projector runs is vastly different and even the way an image looks is not the same. With DLP, white light from the lamp is processed through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of creating an image casts a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to produce the image elements. The elements of the image are projected in sequence on the screen, one colour at a time. The viewer’s eye will then draw each coloured element of the image into the full image. From LCD projectors, all colours are available all the time to create the highest brightness and fantastic colour accuracy. In DLP, only one colour is available at any given time, causing lower colour brightness and accuracy. Some manufacturers have included a white segment for the colour wheel to improve general brightness, but this then detracts from colour accuracy.
I find in forums all the time that DLP provides a higher contrast ratio and thus must be superior. 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 system is capable of. DLP projectors do have high contrast specifications as compared to the majority of LCD projectors. At a glance, this can seem to be an advantage, however, in reality, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be fooled by contrast specifications on websites and in brochures.
When the content you wish to view includes moving images, DLP projection technology also has image marks, or ‘artifacts’. The most typical artifact that a DLP projector creates with moving images is colour break up. Colour break up is to be expected in DLP systems because moving images change between the time red, blue and green colours are projected. LCD projectors do not have this downside because the colours are projected at once. DLP designers have formed 3DLP solutions using 3 chips to solve the colour break up issue, but the cost of these projectors make them hardly practical for the large part of businesses and consumers.
Another differentiation between LCD and DLP is how they compensate for the refractive qualities of light. Jump back to high school science, and remember how the various colours of light refract various amounts when shone through the same lens. The downside 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 obviously not the same and refract light in a different way. Often with a DLP projector, some yellow colour will appear above and some blue will be projected below something as simple as a single black line. In manufacturing LCD projectors can be adjusted to take away these effects on the projected image, because each colour is refracted on a separate LCD panels.
The isolated true buy point (excluding price) with taking a DLP projector is its smaller size and weight. However, this is only relevant to transporting the device and cannot be traded off against the image benefits of LCD projectors. If the outcome of the picture quality is important to you, then the decision is easy. Take an LCD projector! LCD projectors will definitely show bright, colourful images with fewer image imperfections. If you need to learn more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager of Projector Central, Australia’s number one online store for projectors. Based in Brisbane, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
