Projectors: LCD Verses DLP (The downfall of DLP technology)
The most common question customers ask when buying a new projector for the home, office, or classroom is: should I get an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, an acronym for ‘digital light processing’ are the two most common projector imaging technologies. With so many brands and different models available, it can be confusing for consumers to decide between those technologies. Ultimately LCD projectors have superior image quality and colour accuracy. The following article will explain why DLP projectors struggle with creating an equal level of image quality.
Imagine a set of blinds in your household covering your bedroom window. By pulling on a rod you can have the shutters open or closed, depending on if you want to let light in or not. That is exactly how an LCD projector functions. Each pixel operates like a unique shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as experts like to call them. Each pixel element works 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 extremely important for 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 stand alone LCD panels. The 3 LCD panels make the elements of the image by processing each pixel on and off. The pixels are then combined in a glass prism to send the projector image. Something important to remember about LCD projectors is that all three colours are projected onto your projected surface simultaneously. The way a DLP projector works is widely different and even how an image comes out 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 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 create the image elements. The elements of the image are cast in sequence on the screen, one colour at a time. The viewer’s eyes will then put together each coloured element of the image into a total image. With LCD projectors, all colours are available all the time to deliver the top level of brightness and fantastic colour accuracy. In DLP, only one colour is available at once, and so resulting in lower colour brightness and accuracy. Some developers have placed a white segment for the colour wheel to improve general brightness, but this goes and lessens colour accuracy.
I find in forums all the time that DLP provides a higher contrast ratio and ergo 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 possess high contrast specifications as compared to a majority of LCD projectors. Initially, this can seem to be a plus, however, in real life, the true black level is determined by the ambient light in the room in which the projector is being used. Do not be duped by contrast specifications on websites and in brochures.
When the content you want to bring to life 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 unavoidable 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 all the colours are projected simultaneously. DLP builders have created 3DLP solutions using 3 chips to answer the colour break up problem, but the cost of these projectors make them hardly practical for the large part of businesses and consumers.
Another difference between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and they taught you how different colours of light refract various amounts when projected through the same lens. The disadvantage 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 different and refract light in a different way. Often with a DLP projector, some yellow colour will show above and some extra blue will come up below something as simple as a straight black line. In building LCD projectors can be adapted to remove these effects on the projected image, because each colour is processed on its own LCD panels.
The sole actual plus (excluding price) with deciding on a DLP projector is its smaller size and weight. However, this is only relevant in regard to portability and needs to be traded off against the image benefits of LCD projectors. If the result of the picture quality is vital to you, then the answer is simple. Take an LCD projector! LCD projectors will consistently produce bright, colourful images with fewer image mistakes. If you want to learn more about LCD technology in more detail, check out this fabulous resource website: Explore 3LCD. If you have any more questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager with Projector Central, Australia’s leading online store 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.
Sphere: Related Content