Led Display Glossary
Led Display Glossary Terms and Definitions for LED displays
C.D.M.
C.D.M. is the acronym of “Candela per Square Meter” (cd/m2 or cd/sqm ). Nit is a non-SI name also used for this unit. 1 Candela is equal to 1 NIT. It is often used to quote the brightness of led display.
Color Levels
In the LED display industry are considered the color’s levels of Red, Green and Blue, also knows as the three primary colors. Higher is the number of possible nuances, higher is the quality and the naturalness of the visualized image.
Color Temperature
Color temperature is a characteristic of visible light and it is measured in Kelvin degrees. Higher color temperatures (5000 K or more) are “cool” (green–blue) colors, and lower color temperatures (2700–3000 K) “warm” (yellow–red) colors. The color temperature needed to get the Pure White is aprox 6000 kelvin degrees.
Contrast Level
Contrast in visual perception is the difference in appearance of two or more parts of a field seen simultaneously or successively (hence: brightness contrast, lightness contrast, color contrast, simultaneous contrast, successive contrast, etc.). In the led display we use it as the difference between the light emitted by the display and the environmental light reflected by the display’s surface. Minor is the light reflected, higher is the contrast and therefore the cleanliness and naturalness of the images.
Definition of led screen
In the led display industry field we call “Definition” the display’s total number of horizontal and vertical LED lamps. The term “Resolution” is referred to the single module of 1square meter, while the definition is referred to the whole display (once all the led modules have been assembled to form the final led screen ).
DVI
The Digital Visual Interface (DVI) is a video interface standard designed to provide very high visual quality on digital display devices such as flat panelLCDcomputer displays and digital projectors. It was developed by an industryconsortium, the Digital Display Working Group (DDWG). It is designed for carrying uncompresseddigital video data to a display. It is partially compatible with the High-Definition Multimedia Interface (HDMI) standard in digital mode (DVI-D), and VGA in analog mode (DVI-A).
Gamma Correction
The term gamma correction means doing graphics color math accounting for the distortion that the color will eventually go through when displayed on a monitor. Gamma correction controls and manages the brightness and cleanliness of the images.
IP Protection
It means the degree of protection against dust and water. It is identified as IP acronym of “Ingress Protection”. Please see our scheme.
LED
Is the acronym of “Light Emitting Diode”. LEDs appear to be bulbs but in fact are not. LED’s are tiny semiconductors encapsulated in plastic (epoxy) which protect their electronic components and help focus the light. The led lamps might have different colors Red, Green, Blue, Amber, White, UV and it depends of the semiconductor on it ( the chip ) and not by the color of plastic.
Led lamps life expectancy
many companies says that theled lamp life, expectancy is equal to 100,000 hours,….that is absolutely a wrong infos since the led lamps have not such “useful life” ( I mean that a led lamp can have even a longer life, but it is useless for our visual scope ). I will explain this particular and important unknow secret ( and many more ! ) only to those company that become our partner and will get the free training to our factory in Shenzhen.
Lumen
Luminance
Luminance is a photometric measure of the density of luminous intensity in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. It is measured in candela per square meter (cd/m2 or cd/sqm ).
mCd
mCd is the acronym of millicandela (or mCd = CD/1000).
1000 millicandela equals 1 candela (CD).
It is the unit of measure commonly used to describe LED brightness. Candela measures how much light is produced as measured at the light source.
1000 millicandela equals 1 candela (CD).
It is the unit of measure commonly used to describe LED brightness. Candela measures how much light is produced as measured at the light source.
Pitch
It’s the distance between two pixels, expressed in millimetres. It is a fundamental measure as it defines the image’s quality, the displays minimum viewing distance and besides it affect significantly the final cost of the maxi-display. Small pitch display have higher price compared to a larger pitch display.
Pixel
It’s the luminous dot typical of every LED visualization device. It can be composed by one or more LEDs. Normally there are 3,….4,……8 led lamps per pixel. Yes, we can also produce pixel with a large number of led lamps.
Readeability
It’s the maximum distance within the images visualized on the LED display are readable, therefore clearly recognizable by the viewers.
Refresh Rate
The refresh rate is the number of times in a second that display hardware draws the data it is being given. This is distinct from the measure of frame rate in that the refresh rate includes the repeated drawing of identical frames, while frame rate measures how a video source can feed an entire frame of new data to a display.
Rental Display
Rental displays are specifically designed to guarantee lightness and portability of the cabinets ( we use aluminium material to produce rental cabinet ) but also strength and solidity of a structure.
Resolution
It the number of LEDs mounted on every square meter. Obviously higher is the number of LEDs, better is the image quality. It is important to note that smaller is the pitch, higher is the resolution.
R.G.B.
Is the acronym of Red, Green, Blue colors. A mix of proportion 3:6:1 form the white color.
SMD Top Led
The S.M.D. is the acronym on “Surface Mounting Device” ( the component ) while the S.M.T. stands for Surface-mount technology (SMT) is a method for constructing electronic circuits ( the technology ). An SMT component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a matrix of solder balls (BGAs), or terminations on the body of the component.
Viewing Angle
A display viewing angle is the angle within which the brightness of the display is reduced by 50% of the frontal luminosity. For example, a display with a frontal brightness of 5000 NIT (NIT = millicandels for m2) has a viewing angle equal to the angulation in which its brightness is reduced to 2500 NIT.
Virtual Pixel
Virtual Pixel technology is able to control every single LED. This particular and exclusive screen management feature allows overlying every single pixel to the next one, creating a so-called “virtual pixel” (a pixel that does not exist but is perceptible by the human eye).
Visibility
In the led display industry this term is ( aproximately ) the double of the readability distance and so it is the max distance within the LED display is able to capture the attention of the viewer, even if the images/text showed into the led display are not perfectly recognizable.
Glossary of Terms
Need help figuring out what all those technical terms mean? Below is a glossary to help you understand what it is all about.
Approach: 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.
Bi-directional diagnostics:
Two-way communication between a display and its controller. Bi-directional diagnostics assist in pre-maintenance, maintenance, and troubleshooting.
Billboard:
Large format advertising displays intended for viewing from extended distances, generally more than 50 feet.
Circulation:
Traffic volume in a market.
Contrast ratio:
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.
Controller:
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.
Daily Impressions:
Also called DEC (Daily Effective Circulation). The estimated number of persons passing an outdoor location on an average day.
DEC:
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).
Degradation:
The standard method used to express the life of a display is the time it takes to reach 50% of its day one brightness.
Dial-up:
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.
Digital Subscriber Line (DSL):
An internet connection that can be permanently connected and delivers higher data rates than a dial-up connection.
Dimming:
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.
Diode:
Also called light-emitting diode (LED). See light-emitting diode.
DVI:
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.
Enhanced Pixel Resolution:
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.
Expected lifetime:
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).
Exposure:
Represents the reasonable opportunities for advertising to be seen and read. Common to all media.
Face:
The surface area on an outdoor unit where advertising copy is displayed. A unit may have more than one face.
Frequency:
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.
Gamma correction:
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.
Impression:
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.
IP65:
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.
Intensity:
Often called brightness. The LED industry measures display intensity in candelas per square meter, which is also referred to as nits.
LED brightness:
The brightness level of an LED is measured in milli-candelas. The materials used to manufacture the LED determines the brightness of the LED.
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.
Line of Sight:
The simultaneous viewing of more than one outdoor unit.
Matrix:
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).
Milli-candela (mcd):
One thousandth of a candela
Nit, nits:
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.
Out of Home:
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.
Outdoor Advertising:
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.
Panels:
A cluster of modules built into a housing.
Physical Pitch Resolution: 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.
Pitch:
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.
Proof-of-Performance:
Certification by an outdoor company that contracted advertising services have been rendered.
Reach:
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.
Readability Angle:
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)
Refresh rate:
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.
Remote control:
Control of a display from a remote and/or central location via a communications network.
Resolution:
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.
RGB:
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.
Sign:
Any structure used to display information regarding a product or service. An outdoor unit is a sign.
Spectacular:
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.
Traffic Count:
The recording of the vehicles and pedestrians passing a given point; used by TAB to authenticate the potential exposure of outdoor advertising structures.
Viewing Angle:
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.
Viewing Distance:
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.
Visual Resolution:
The effective resolution on the display as perceived by the human eye.
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