What are they talking about?!?
Digital/HDTV Terms that Begin with L123
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LCD (Liquid Crystal Display)
Liquid Crystal Display technology is one of the methods used to create flat-panel TVs. Light isn't created by the liquid crystals; a light source (bulb) behind the panel shines light through the display. The display consists of two polarizing transparent panels and a liquid crystal solution sandwiched in between. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal acts like a shutter, either allowing light to pass through or blocking the light. The pattern of transparent and dark crystals forms the image.
LCD technology is used in direct-view, rear-projection, and front-projection TVs, and is fundamentally different from the CRT technology used in conventional TVs.
LCoS (Liquid Crystal on Silicon)
A projection TV display technology that sandwiches a layer of liquid crystal between a cover glass and a highly reflective, mirror-like surface patterned with pixels that sits on top of a silicon chip. These layers form a microdisplay that can be used in rear-projection and front-projection TVs.
Laser Disc
Now-defunct 12-inch disc format with excellent analog, FM-recorded video image, and either analog or CD-quality PCM-encoded audio. Later discs used one of the analog channels to record an RF-modulated Dolby Digital/AC3 soundtrack and/or used the PCM tracks to encoded a DTS soundtrack.
Letterbox
The term used to describe the way a 16:9 aspect ratio image is displayed on a 4:3 screen, where black areas are visible above and below the image.
LFE (Low Frequency Effects track)
The .1 channel of a Dolby Digital, DTS, or SDDS soundtrack. The LFE is strictly low-frequency information (20 to 120 Hz, with 115 dB of dynamic range) that’s added to the soundtrack for extra effect. This track does not inherently contain all the bass of the soundtrack.
Light Output
Measures the amount of light produced by a front projector. Expressed in "lumens" or "ANSI lumens," with a higher number indicating greater light output.
Line Doubling
A method, through special circuitry, to modify an NTSC interlaced picture to create an effect similar to a progressively scanned picture. The first field of 262.5 odd-numbered lines is stored in digital memory and combined with the even-numbered lines. Then all 525 lines are scanned in 1/30th of a second. The result is improved detail enhancement from an NTSC source.
Line-Level (Low-Level)
A level of electrical signals too low to make the
average speaker move sufficiently. Amplifiers receive line-level signals and amplify them to speaker level.
LNB (Low-Noise Blocker)
The receiving end of a satellite dish.
Lumen
The unit of measure for light output of a projector. Different manufacturers may rate their projectors' light output differently. "Peak lumens" is measured by illuminating an area of about 10% of the screen size in the center of the display. This measurement ignores the reduction in brightness at the sides and corners of the screen.
The more conservative "ANSI lumens" (American National Standards Institute) specification is made by dividing the screen into 9 blocks, taking a reading in the center of each, and averaging the readings. This number is usually 20-25% lower than the peak lumen measurement.
Luminance
The black and white (Y) portion of a composite, Y/C, or Y/Pb/Pr video signal. The luminance channel carries the detail of a video signal. The color channel is laid on top of the luminance signal when creating a picture. Having a separate luminance channel ensures compatibility with black-and-white televisions.
