USB Movie Reviews

Projectors: LCD Verses DLP (The downfall of DLP technology)

The most common question asked when buying a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, an acronym for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most popular projector imaging technologies. With so many business brands and types available, it can be confusing for clients to decide between the two technologies. The simple fact of the matter is that LCD projectors give superior image quality and colour accuracy. The article below tells you why DLP projectors struggle with reproducing the same level of image quality.

Think of a set of blinds in your home on your bedroom window. With the twist of a rod you can turn the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector functions. 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 constructed 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 when the projector is turned on to when the picture reaches your screen is vitally significant with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which project the coloured light to 3 individual LCD panels. The 3 LCD panels create the elements of the image by switching each pixel on and off. The pixels are then simultaneously processed in a glass prism to deliver the projector image. A point to understad about LCD projectors is that all three colours are projected onto your projected surface at the same time. The way a DLP projector operates is widely different and even the produced 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 method of forming an image forms 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 sent in sequence on the screen, one colour at a time. The viewer’s vision will then put together each coloured element of the image into the total image. Using LCD projectors, all colours are available all the time to create top brightness and fantastic colour accuracy. In DLP, just one colour is available at any given time, and so resulting in lower colour brightness and accuracy. Some manufacturers have included a white segment for the colour wheel to improve brightness overall, but this goes and lessens colour accuracy.

I read in forums all the time that DLP gives a higher contrast ratio and ergo must be superior quality. 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 system is capable of producing. DLP projectors do offer high contrast specifications when compared to many LCD projectors. At first glance, this seems to be a benefit, however, in reality, the true black level is determined by the ambient light in the room while the projector is in use. Do not be tricked by contrast specifications on websites and in brochures.

When the content you want to view needs moving images, DLP projection technology also has image marks, or ‘artifacts’. The most often seen artifact that a DLP projector displays 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 pulled up. LCD projectors do not have this problem because the colours are sent simultaneously. DLP manufacturers have developed 3DLP solutions using 3 chips to resolve the colour break up issue, but the price tag of these projectors make them hardly practical for the majority of 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 recall how the various colours of light refract various amounts when shone through the same lens. The disadvantage with DLP projectors is that they have 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. Generally with a DLP projector, a spill of yellow colour will be projected above and an extra blue will show below an image as simple as a straight black line. In building LCD projectors can be set to remove these effects on the projected image, as each colour is directed on separate LCD panels.

The one veritable plus (excluding price) with deciding on a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to portability and must be traded off against the image plusses of LCD projectors. If the outcome of the picture quality is crucial to you, then the choice is simple. Choose an LCD projector! LCD projectors will always create bright, colourful images with fewer image blips. If you want to know more about LCD technology in more detail, check out this fantastic 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 at Projector Central, Australia’s top online store for projectors. Brisbane-based, Projector Central has served Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.