Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question asked when looking for a new projector for the home, office, or classroom is: would I buy an LCD projector or a DLP projector? LCD, standing for ‘liquid crystal device’ and DLP, standing for ‘digital light processing’ are the two most popular projector imaging technologies. With so many company brands and types available, it can be overwhelming for consumers to make a decision between these technologies. The simple fact of the matter is that LCD projectors have better image quality and colour accuracy. The next paragraph will explain why DLP projectors struggle with projecting the same level of image quality.
Think of a set of blinds in your house for your bedroom window. With the twist of a rod you can make the shutters open or closed, depending on if you want to let light in or not. And such is exactly how an LCD projector behaves. Each pixel works like a single shutter on a set of blinds to either shine light through or to block it. DLP on the other hand is created of millions of microscopic mirrors or ‘pixel elements’ as pros 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 switches on to when the picture reaches your screen is extremely important to image quality, brightness and colour accuracy. LCD projectors shine white light from the lamp by splitting 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 switching each pixel on and off. The pixels are then combined in a glass prism to send the projector image. Something to know about LCD projectors is that all three colours are directed onto your projected surface simultaneously. The way a DLP projector operates is widely different and even the final product of how an image comes out is not the same. With DLP, white light from the lamp is sent through a rotating colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of projecting 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 create the image elements. The elements of the image are projected 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 whole image. Using LCD projectors, all colours are available all the time to form the highest brightness and spectacular colour accuracy. In DLP, just one colour is available at a time, and so resulting in lower colour brightness and accuracy. Some DLP manufacturers have put a white segment into the colour wheel to improve overall 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 superior quality. 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 machine is capable of. DLP projectors do possess high contrast specifications in comparison to most LCD projectors. At first glance, this appears to be an advantage, however, in the real world, the true black level is determined by the ambient light in the room in which the projector is being utilised. Do not be duped by contrast specifications on websites and in brochures.
When the content you wish to bring to life includes moving images, DLP projection technology can also create image errors, or ‘artifacts’. The most often seen 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 projected. LCD projectors do not have this downside because all the colours are projected at the same time. DLP developers have created 3DLP solutions using 3 chips to fix the colour break up artifacts, but the price tag of these projectors make them almost impossible for most businesses and consumers.
Another point of difference between LCD and DLP is how they compensate for the refractive qualities of light. Jump back to high school science, and recall how various colours of light refract differing amounts when passing through the same lens. The disadvantage with DLP projectors is that they use the one same panel with the same lens to project Red, Blue and Green. All 3 colours are not the same and refract light in a different way. Often with a DLP projector, some yellow colour will appear above and an extra blue will appear below something as simple as a single black line. In building LCD projectors can be adjusted to take away these effects on the projected image, because each colour is projected on its own LCD panels.
The one veritable advantage (excluding price) with choosing a DLP projector is its smaller overall size and weight. However, this is only relevant to transporting the device and has to 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 easy. Go with an LCD projector! LCD projectors will constantly create bright, colourful images with fewer image blips. If you wish to learn more about LCD technology in more detail, check out this fantastic resource website: Explore 3LCD. If you have any further questions, visit Projector Central and send me an email.
Jonathan King is the sales and marketing manager for Projector Central, Australia’s number one online shop for projectors. Brisbane-based, Projector Central has been servicing Australia for 15 years. For data projectors in the Gold Coast and Interactive Whiteboards, contact Projector Central today.
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