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The most common question that is asked when purchasing a new projector for the home, office, or classroom is: will I buy an LCD projector or a DLP projector? LCD, which stands for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two commonplace projector imaging technologies. With so many business brands and models available, it can be challenging for customers to make a decision between both technologies. The simple fact of the matter is that LCD projectors give far better image quality and colour accuracy. The next part of this article explains why DLP projectors struggle with reproducing an equal standard of image quality.

Imagine a set of blinds in your room covering your bedroom window. By pulling on a rod you can make the shutters open or closed, according to whether you want to let light in or not. Such is exactly how an LCD projector operates. Each pixel operates 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 professionals 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 is switched on to when the content reaches your screen is absolutely important with regard to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by cutting it into red, blue and green components, by three mirrors which send the coloured light to 3 individual LCD panels. The 3 LCD panels cast the elements of the image by shining each pixel on and off. The pixels are then projected in a glass prism to deliver the projector image. A point to know about LCD projectors is that all three colours are directed onto your projector screen all at the same time. The way a DLP projector functions is totally different and even how 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 projecting 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 combine each coloured element of the image into a full image. In LCD projectors, all colours are available all the time to deliver the top level of brightness and great colour accuracy. In DLP, only one colour is available at once, causing lower colour brightness and accuracy. Some designers have included a white segment for the colour wheel to improve brightness overall, but this further lessens colour accuracy.

I hear in forums all the time that DLP provides a higher contrast ratio and as such must be superior. For those who don’t 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 capable of. DLP projectors do offer high contrast specifications in comparison to many LCD projectors. At first glance, this must be an advantage, however, in the real world, the true black level is determined by the ambient light in the room while the projector is used. Do not be duped by contrast specifications on websites and in brochures.

When the content you wish to see includes moving images, DLP projection technology can also have image marks, 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 between the time red, blue and green colours are shone. LCD projectors do not have this disadvantage because every colour is projected with the others. DLP builders have come up with 3DLP solutions using 3 chips to resolve the colour break up error, but the expense of these projectors make them almost impossible for the large part of businesses and consumers.

Another differentiation between LCD and DLP is how they compensate for the refractive qualities of light. Think back to high school science, and remember when they taught you how different colours of light refract different amounts when passing through the same lens. The downfall with DLP projectors is that they utilise 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. Generally with a DLP projector, a superfluous yellow colour will show above and a superfluous blue will show below something as simple as a straight black line. While being built LCD projectors can be fixed to minimize these effects on the projected image, because each colour is processed on its own LCD panels.

The sole veritable advantage (excluding price) with going with a DLP projector is its smaller total size and weight. However, this is only relevant for transporting the device and must be traded off against the image superiority of LCD projectors. If the outcome of the picture quality is important to you, then the decision is simple. Take an LCD projector! LCD projectors will consistently create bright, colourful images with fewer image mistakes. If you need to find out more about LCD technology in more detail, check out this tremendous resource website: Explore 3LCD. If you have any other questions, get onto Projector Central and send me an email.

Jonathan King is the sales and marketing manager of Projector Central, Australia’s leading online store for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.

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