Display Definitions

LCD Technology: click to enlarge LCD (Liquid Crystal Display)
LCD projection technology is the current leader of the pack, having captured the majority of the market share of all projectors sold. Most LCD projectors have three panels. Each panel is a prism that allows blue, red, or green light through its pixels. These separate colors are then converged and projected. Electrical signals turn on pixels within a set based on the resolution of the unit. LCDs are known to produce greater color definition, offering more shades or variations of color than single-chip DLP™ projectors. DLP™ projectors can sometimes burn definition out of the highlights and shadows with their vibrant colors. Newer LCD projectors include special optics enhancers like micro-lens array that minimize pixelization known as the "screen door effect." New LCD projectors have contrast ratios as high as 800:1. By comparison, DLP™ projectors contrast ratios are as high as 3000:1. The portability and brightness of LCD projectors have made them a popular choice for traveling presenters. The lightest LCD projectors weigh-in at about 4 lbs.
Click for larger image.

1 chip DLP: click to enlarge DLP™ (single chip) - Digital Light Processing
The single-chip DLP™ is the most portable of all our players. Currently you can find single-chip DLP™ projectors that weigh less than 2 pounds. Digital Light Processing is the product of the great minds at Texas Instruments. DLP™ uses a single Digital Mirror Device (DMD) chip that has thousands of tiny mirrors, each representing a single pixel. These mirrors tilt back and forth and deflect light as indicated by the source to create the image. One limitation of DLP™ technology thus far is brightness. Currently most of the brightest single-chip DLP™ projectors on the market are just 3,000 lumens compared to the 6,000+ lumens of comparably priced LCD's and three-chip DLP™ projectors. Brighter single chip DLP™ projectors are available, but are significantly more expensive. However, because of their deep, rich blacks and high contrast ratios, LP™ projectors have been a popular choice among home theater enthusiasts.
Launch a Flash demo of how DLP(tm) technology works.
Image and Flash demo reproduced courtesy of Texas Instruments

3 chip DLP: click to enlarge DLP™ (three-chip) - Digital Light Processing
The three-chip DLP™ has the best looking images of all the players. The three-chip system is much like the single-chip DLP™ only better. The image quality of the three-chip DLP™ is unsurpassed. Unfortunately it is also the most expensive. Today's three-chip™ DLP projectors cost anywhere from $15,000-$30,000 or higher. Unlike CRTs and single-chip DLP™ projectors, three-chip DLP™ can have very high lumen output levels.
Click for larger image.
Image reproduced courtesy of Texas Instruments


CRT model CRT- Cathode Ray Tube
This is the largest and most experienced player. Many of you have probably seen this kind of projector at a sports bar or in an auditorium at a school. CRT utilizes three tubes, sometimes called 'guns.' The three colors combine or converge to make your image. CRTs do not have a fixed number of pixels, making them versatile machines capable of clear images from higher or lower resolution sources. CRTs also require periodic 'calibration' by a trained professional, which can mean additional expense for the end user down the road. These projectors are generally used in fixed installations because of their size. CRTs are typically not as bright as the other technologies, but the refined picture quality of a properly calibrated CRT is tough to beat.


Plasma Flatscreen model Plasma Display Panel (aka Flatscreen TV)
Arguably our 'coolest' player is the Plasma display panel. It is much thinner than other direct view display devices (i.e. TV), making it easy to mount to a wall without interrupting the flow of a room. From a technical perspective, a plasma screen is basically a direct view of thousands of pixels (made of glass bubbles) filled with Xenon gas in a plasma state. Inside each bubble are three cavities, one blue, one red and one green. Each bubble is hooked up to an electrical current. That current is then triggered by information from your input device. Since you are looking directly at the source of the image (the bubbles) you get a vivid and rich color. Plasmas are cool, but are not inexpensive. Watch for plasma prices to drop, making them a great choice for direct view televisions.
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Image reproduced courtesy of Hitachi

LCOS chip

LCoS - Liquid Crystal on Silicon
The newest player in the game, LCoS is a kind of combination of LCD and DLP technologies. LCoS is liquid crystal on a silicone wafer, with a very high pixel density. The number of pixels are less restricted than LCD or DLP because the electronics can be placed under the pixel rather than next to it. The high pixel density means higher resolution. In fact, today's LCoS projectors start at SXGA resolution. The high pixel density also means no 'pixelization.'
Image courtesy of Hitachi

Holographic Images on Transparent Screen

Holographic Images on Transparent Screen
Several manufacturers are working on a new and also very chic technology. A projector shines on a thin Holographic screen attached to a transparent surface like glass or plexi-glass. The effect is an image that appears to float in mid-air, which is sure to get attention. Expect to see this hot new display at a store front near you.
Image courtesy of Hitachi




OLED example OLED - Organic Light Emitting Diode
What is OLED (organic light emitting diode) technology? Experts predict that the new technology will have a billion dollar market by 2007. The implications of the new technology are remarkable, although the impact will not be felt for a few years. Unlike a CRT monitor, plasma display, or LCD monitor, the OLED uses emissive technology. This means that the screen itself emits light, and therefore doesn't require additional hardware for creating light, like tubes or lamps. Less hardware means less bulk. In fact, the screen could be as thin as a piece of paper, as shown here. Today you can find some OLED technology in cell phones, PDAs, and car stereos. In a few years, you may find OLED technology on laptop computers, car instrument panels, and perhaps even a portable presentation device that can be easily rolled up and stowed away.
(Sources: Stanford Resources, December 2001)
Image reproduced courtesy of Universal Display Corporation.

LCD TV example from BenQ LCD Television - Liquid Crystal Display
Your old TV has some new competition -- innovative new Liquid Crystal Display (LCD) flat panel televisions. Like popular LCD monitors you commonly see used with computers, LCD TV's have a slim design and a flat viewing surface, but have been fine tuned for video display. Recent advances in flat panel LCD technology now allow for larger screens, wider viewing angles, and higher-quality video images. LCD TV's are also competition for trendy-but-heavy, plasma display technology. They are several times lighter than comparably sized plasmas, and are far more durable.

How do LCD TV's work? Two sheets of polarized transparent material, one with a special polymer coating that holds liquid crystals, are adhered together. Electric current is passed through individual crystals, which interpret the information from the broadcast signal to allow or disallow light through them to create the specified image. The crystals themselves do not produce light, so the technology is non-emissive and therefore does not give off radiation like an older TV does. Florouescent tubes housed behind the transparent material are used to illuminate the image, so they require less power to operate than CRT televisions and plasma displays.

Image reproduced courtesy of BenQ