Q: DLP, LCD, Plasma, Huh?

A Guide to the Alphabet Soup of Video Display Technologies

Several video display technologies are available today, and each has its strengths and weaknesses. Knowing those can allow you to better determine which one is right for you. One key determinant is called black level, or the ability to show true blacks. Also look for gradations of gray, so you can see details in dark scenes.

CRT

Cathode ray tubes are used in direct-view TVs (one tube) and some front and rear projectors with three tubes or "guns" for red, green and blue.

Advantages: They're inexpensive and can produce the most film like images.

Disadvantages: They require bulky and heavy chassis.

DLP

Digital light processing works by reflecting light off of millions of microscopic mirrors embedded on computer chips. More expensive DLP front projectors use three chips to produce red, green and blue, while less expensive single-chip front- and rear- projection sets spin a color wheel in front of the reflected light to produce the full spectrum of colors.

Advantages: Bright pictures, lighter-weight projectors and rear-projection sets.

Disadvantages: Can produce some video artifacts.

LCoS

In liquid crystal on silicon, liquid crystals are coated onto silicon chip with a reflective layer to increase contrast and provide a smooth image. Forms of LCoS include JVC's D-ILA and HD-ILA (Direct Image Light Amplifier) and Sony's SXRD (Silicon X-tall [Crystal]) Reflective Display. LCoS is available in one- and three-chip designs, and in front- and rear-projection TVs.

Advantages: Smooth, film like images, great blacks in higher-end models.

Disadvantages: Some uniformity issues.

LCD

Liquid crystal displays in flat panels work by trapping a liquid crystal solution between two sheets of polarized glass and passing an electric current through the liquid crystals. Most LCD panels are backlit. 3LCD for rear-projection sets utilizes three LCD wafers and a powerful lamp to throw an image onto a screen with one lens instead of three.

Advantages: Good for rooms with glare. Lower prices than plasma in flat panels up to 50 inches.

Disadvantages: Lower-resolution sets can show a screen-door effect. Some LCDs show motion blur in fast scenes. Viewing at angles is improving but still limited.

Plasma

A plasma display panel (PDP) has gas that illuminates cells when it is electrically excited.

Advantages: Uniform brightness, good blacks, better viewing angles than LCDs.

Disadvantages: Susceptible to glare. More expensive than LCDs up to 50 inches. Images left on can "burn in" to a screen. They also use a lot of electricity.