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L

LED (Light Emitting Diode)
A solid-state component that uses a semiconductor (a silicon chip or some other type of semiconductor) that emits visible light when electric current passes through it. LED illumination is monochromatic, occurring at a single wavelength, and the output can range from red to blue-violet, green, amber, and white. An LED consists of two elements of processed material called P-type semiconductors and Ntype semiconductors. These two elements are placed in direct contact, forming a region called the P-N junction. In this respect, the LED resembles most other diode types, but there are important differences. The LED also has a transparent package, allowing visible energy (or in some cases infrared energy) to pass through. The PN-junction of LED's is larger than that of other diodes, too, and its shape is tailored to the application.

LED Brightness
The brightness level of an LED is measured in millicandelas. The materials used to manufacture the LED determine the brightness of the LED.

Light detector, light sensor
An electrical component used to detect the amount or level of ambient light surrounding a display. If dimming has been set to "AUTO," the light detector or sensor adjusts the intensity of the LED accordingly.

Line
The side of a highway or street on which an outdoor units is positioned.

Line of Sight
The simultaneous viewing of more than one outdoor unit.

Load Factor
The average number of persons riding each vehicle. Determined through national research and syndicated and government research reports. The current load factor for adult 18+ vehicle occupancy is 1.38.

Location List
A listing of all locations included in a specific outdoor program.

Luminance
The amount of visible light leaving a point on a surface in a given direction. This "surface" can be a physical surface or an imaginary plane, and the light leaving the surface can be due to reflection, transmission, and/or emission. The standard unit of luminance is the candela per square meter (cd/m2). As used in video applications, luminance is the degree of brightness (black and white portion of the video signal) at any given point in the video image. A video signal is comprised of luminance, chrominance (color information), and synchronization. If luminance is high, the picture is bright, and if low, the picture is dark. Changing the chrominance does not affect the brightness of the picture (see nit).

 

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