Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question heard when purchasing a new projector for the home, office, or classroom is: do I purchase an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two top projector imaging technologies. With so many business brands and different models available, it can be confusing for consumers to decide between those technologies. The simple fact of the matter is that LCD projectors provide superior image quality and colour accuracy. The next part of this article will explain why DLP projectors struggle with projecting a similar level of image quality.
It’s like a set of blinds in your room over your bedroom window. By pulling on a rod you can turn the shutters open or closed, depending on if you want to let light in or not. And that is exactly how an LCD projector operates. Each pixel functions 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 professionals like to call them. Each pixel element works to either reflect light or block it.
How the light source is processed from the point at which the projector switches on to when the image reaches your screen is ultimately significant with regard to image quality, brightness and colour accuracy. LCD projectors direct 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 cast the elements of the image by processing each pixel on and off. The pixels are then combined in a glass prism to form the projector image. A significant point to remember about LCD projectors is that all three colours are delivered onto your projected surface all at once. The way a DLP projector runs is very different and even how an image shows up is not the same. With DLP, white light from the lamp is directed through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of making an image creates a sequence of red, blue and green light. The millions of micro mirrors as mentioned above reflect the coloured light on the pixels to construct 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 put together each coloured element of the image into the single total image. Using LCD projectors, all colours are available all the time to form the top level of brightness and great colour accuracy. In DLP, only one colour is available at a time, and so resulting in lower colour brightness and accuracy. Some developers have put a white segment for the colour wheel to improve brightness generally, but this goes and lessens colour accuracy.
I hear in forums all the time that DLP has a higher contrast ratio and thus must be superior. For those who are 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 machine is capable of. DLP projectors do have high contrast specifications in comparison to a majority of LCD projectors. At one glance, this can seem to be an advantage, 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 want to see requires moving images, DLP projection technology can also have image marks, or ‘artifacts’. The most common artifact that a DLP projector shows with moving images is colour break up. Colour break up is incontrovertible in DLP systems because moving images change position between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because every colour is processed with the others. DLP builders have come up with 3DLP solutions using 3 chips to fix the colour break up artifacts, but the price of these projectors make them almost impossible for most businesses and consumers.
Another variance between LCD and DLP is how they compensate for the refractive qualities of light. Remember back to high school science, and remember how different colours of light refract different amounts when projected through the same lens. The disadvantage 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 different and refract light at different levels. Often with a DLP projector, some yellow colour will come through above and an extra blue will come through below an image as simple as a single black line. During manufacturing LCD projectors can be set to take away these effects on the projected image, because each colour is projected on its own LCD panels.
The one true buy point (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to portability and has to be traded off against the image benefits of LCD projectors. If the result of the picture quality is vital to you, then the solution is simple. Choose an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image imperfections. If you desire to know more about LCD technology in more detail, check out this spectacular resource website: Explore 3LCD. If you have any further questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s leading online provider for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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