Projectors: LCD Verses DLP (The downfall of DLP technology)
The typical question heard when purchasing a new projector for the home, office, or classroom is: will I purchase an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two top projector imaging technologies. With so many different brands and models available, it can be confusing for clients to make a choice between both technologies. The fact is that LCD projectors offer better image quality and colour accuracy. The article below will explain why DLP projectors struggle with creating a comparable rate of image quality.
Think of a set of blinds in your home for your bedroom window. By pulling a rod you can have the shutters open or closed, depending on if 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 send light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as the professionals like to call them. Each pixel element operates to either reflect light or block it.
How the light source is processed from the point when the projector is turned on to when the content reaches your screen is ultimately significant to image quality, brightness and colour accuracy. LCD projectors project white light from the lamp by separating it into red, blue and green components, by three mirrors which send 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 create the projector image. Something important to remember about LCD projectors is that all three colours are directed onto your projector screen simultaneously. The way a DLP projector works is widely different and even how an image appears is not the same. With DLP, white light from the lamp is processed through a turning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This way of creating an image requires a sequence of red, blue and green light. The millions of micro mirrors described 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 vision will then put together each coloured element of the image into a whole image. In LCD projectors, all colours are available all the time to create the top level of brightness and spectacular colour accuracy. In DLP, only one colour is available at a time, and so resulting in lower colour brightness and accuracy. Some designers have placed a white segment into the colour wheel to improve general brightness, but this then lessens colour accuracy.
I hear in forums all the time that DLP has a higher contrast ratio and as such must be better. For those who do not 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 able to produce. DLP projectors do possess high contrast specifications as compared to many LCD projectors. Initially, this can seem to be an advantage, however, in real life, the true black level is determined by the ambient light in the room when the projector is utilised. Do not be hoodwinked by contrast specifications on websites and in brochures.
When the content you plan to project needs moving images, DLP projection technology also creates image imperfections, or ‘artifacts’. The most common artifact that a DLP projector creates with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change position between the time red, blue and green colours are projected. LCD projectors do not have this disadvantage because the colours are delivered at the same time. DLP developers have developed 3DLP solutions using 3 chips to solve the colour break up artifacts, but the price of these projectors make them almost impossible for the majority of businesses and consumers.
Another differentiation between LCD and DLP is how they make up for the refractive qualities of light. Jump back to high school science, and recall how the various colours of light refract various amounts when passing through the same lens. The downside with DLP projectors is that they take 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 extra yellow colour will appear above and an extra blue will be projected below an image of something as simple as a single black line. In manufacturing LCD projectors can be set to take away these effects on the projected image, because each colour is refracted on a separate LCD panels.
The isolated veritable plus (excluding price) with picking a DLP projector is its overall 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 result of the picture quality is important to you, then the solution is a no-brainer. Go with an LCD projector! LCD projectors will constantly show bright, colourful images with fewer image errors. If you desire to learn more about LCD technology in more detail, have a look at this spectacular resource website: Explore 3LCD. If you have any persisting questions, go to Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online provider for projectors. Brisbane-based, Projector Central has serviced Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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