Glossary of LED Terminology

With the growth of the LED display and LED  lighting industries,  you may have heard some unfamiliar lighting terms.  We've created the following glossary of LED terminology to help!

The distance measured along the line of travel from the point where an advertising unit first becomes fully visible to the point where the copy is no longer readable.

Two-way communication between a display and its controller. Bi-directional diagnostics assist in pre-maintenance, maintenance, and troubleshooting.

Traffic volume in a market.

Ratio between the brightness or intensity measurement taken when the screen is displaying a blank video signal and a full, white video signal. This ratio determines the readability of the display so as to measure "depth" of an image or as a measure of how well the image can be seen in high ambient light.

Computer or computer-type device used to program and operate digital displays 
CPM Cost per thousand. The term refers to the cost of reaching one thousand advertising exposure opportunities in a market. Common to all media.

Also called DEC (Daily Effective Circulation). The estimated number of persons passing an outdoor location on an average day.


Daily Effective Circulation. The average number of persons passing and potentially exposed to an advertising display for either 12 hours (unilluminated - 6:00am to 6:00pm) or 18 hours (illuminated - 6:00am to 12:00 midnight).

The standard method used to express the life of a display is the time it takes to reach 50% of its day one brightness.


A temporary, as opposed to dedicated, connection between machines established over a telephone line and using modems. Dial-up also refers to the type of communication the main controller has with a sign. Dial-up indicates that a dialing modem is required to communicate with the sign.

Changing the brightness of a display, or the capability of increasing or decreasing the overall display intensity. The brightness level should be highest during the day to compete with daylight, and lower at night.

Also called light-emitting diode (LED). See light-emitting diode.


Is the acronym of Digital Visual Interface and it is a standard interface. The DVI standard was created to allow the transfer of big quantity of video data in digital format, regardless of the type of monitor utilized.


Represents the reasonable opportunities for advertising to be seen and read. Common to all media.


Anticipated length of use for an LED. The expected lifetime of an LED is measured at the point when the sign has degraded to 50 percent of its original intensity. LEDs have a typical expected life of 50,000 to 100,000 hours (as specified by the manufacturer).


Increases picture definition by utilizing LED pixel sharing technology where LEDS from adjacent pixels are shared to create a new pixel half-way between the real pixels.

The surface area on an outdoor unit where advertising copy is displayed. A unit may have more than one face.

The average number of times an individual has the opportunity to see an advertising message during a defined period of time. Frequency (and reach) in outdoor advertising is typically measured over a four week period.

A process used with video images to correct brightness and internal micro-contrast within the image. Gamma correction allows a change of ratio between the brightest red component and weakest red.


Is a term used by all media to quantify the number of people who have an opportunity to see an ad in a given period of time.

Often called brightness. The LED industry measures display intensity in candelas per square meter, which is also referred to as nits.

The protection classification offered by an enclosure is shown by the letter IP (Ingress Protection) and two digits. The first digit indicates two factors: 


  1. Protection for persons

  2. Protection for equipment

The second digit indicates the protection against water. A rating of IP65 indicates enclosure is totally protected against dust. It also indicates enclosure is protected against low pressure jets if water from all directions - limited ingress permitted.

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.

The brightness level of an LED is measured in milli-candelas. The materials used to manufacture the LED determines the brightness of the LED.

The simultaneous viewing of more than one outdoor unit.

  1. a two-dimensional array, that is, an array of rows and columns. 

  2. the height and width of a display, measured in rows and columns of pixels (for example, 8x48 = eight rows high by 48 columns wide).

One thousandth of a candela.


Nit is defined as a luminance unit equal to one candela (one candle) per square meter measured perpendicular to the rays from the source. From the Latin word nitere, meaning "to shine"; nits are used to measure display intensity, or brightness. Nits, when used in conjunction with contrast ratio and viewing angle, determine the quality of the image in the desired application.



 
All advertising that is specifically intended to reach consumers outside the home. Out of home includes, but is not limited to, outdoor media and radio.

The term refers to many forms of media that carry advertising messages to consumer audiences outside the home. Outdoor products are divided among three primary categories, billboards, street furniture and transit.


A cluster of modules built into a housing.

The measured distance between the same diode within adjacent pixels.

Pixel
The smallest single point of light on a display that can be turned on and off. For LED displays, a pixel is the smallest block of light emitting devices that can generate all available colors. For incandescent displays, a pixel is an individual lamp on the matrix.

The distance from the center of a pixel to the center of the next pixel. Pitch influences the resolution of a LED display that shows images. A small pitch translate to higher resolution. A large pitch translates to larger text/character sizes. The picture to the right indicates how pitch is measured.


Certification by an outdoor company that contracted advertising services have been rendered.

The approximate percentage of a target audience's population which will be potentially exposed to an advertising message at least once during a specified period of time. Reach is normally measured over four week periods. Common to all media.

The angle at which the LEDs on a sign can still be seen and/or read. The readability angle, which is dependent on ambient light and site conditions, is much larger than the viewing angle. For instance, a 30° readability angle LED sign can easily be read at angles greater than 90° at night. In an instance where the LEDs have been dimmed to less than 50 percent, for example, a viewer would still be able to see or read the LEDs, hence the greater angle than in viewing angle. Readability angle is largely subjective and difficult to measure. (see viewing angle)


The number of times per second the screen is updated or "repainted." Depending on the video standard, the actual image is changed only 30 times per second for NTSC signal or 25 times per second for PAL. However, most LED systems use pulse-width modulation to generate the color levels, and if the image were only "painted" once for every change, there would be a noticeable flicker on the display. A refresh rate of greater than 60 times per second will minimize the flicker. In general, LED displays should be refreshed at 120 times per second (120 Hz) or greater.

Control of a display from a remote and/or central location via a communications network.

The basic measurement of how much information is displayed on a screen, expressed in units of pixels. Resolution is determined by the pixel pitch and the physical dimensions of the display. To calculate resolution, divide the area of the display by the area of an individual pixel. Most displays of video quality have a resolution greater than 10,000 pixels. Generally, the greater the resolution, the better the image will appear. Commonly listed as number of pixels per square meter.

Red-green-blue. In video displays, web design, and design for computer monitors, colors are defined in terms of a combination of these three colors. For example, the RGB abbreviation for the color blue is 0-0-255. In contrast, print designers typically define colors using cyan-magenta-yellow-black, or CMYK.

Any structure used to display information regarding a product or service. An outdoor unit is a sign.


A bulletin that is usually larger than 14' x 48' and is positioned at prime locations in a market. A spectacular often utilizes special embellishments.

The recording of the vehicles and pedestrians passing a given point; used by TAB to authenticate the potential exposure of outdoor advertising structures.

The area that will provide optimum viewing of a display. The angle is determined by the horizontal and vertical points at which the measured light intensity is 50 percent of that measured directly in front of the display.


In general, the distance from a sign that text can be read. For digital displays, the maximum viewing distance is gauged by the readability of the entire display. It is generally accepted that for every 1' of display height, there is a viewing distance of 40' (40:1 ratio). For example, an 8' display could reasonably be viewed at a distance of 320'. For traditional matrix displays, the maximum viewing distance is gauged by using the smallest text character (using a 7-pixel-high font). The accepted standard is that displays gain 50' of viewing per inch of character height. For example, using a 7-high font for a 1.5" pixel (character height = 7 pixels x 1.5" = 10.5"), the viewing distance would be 525'. (10.5 x 50' = 525). The minimum viewing distance is defined as the closest distance at which the colors from an individual pixel begin to blend with the surrounding pixels.

The effective resolution on the display as perceived by the human eye.

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