LED Education Center
Dicitonary of Terms
1 Candela = 1 Lumen (scientific measurements of brightness)
Ampere (Amp): Measurement of Electric Current. A unit of electric current equal to a flow of one coulomb per second.
A steel or aluminum housing that contains all of the components that comprise a LED Display. The cabinet typically provides attachment points for handling and mounting the display. Designs vary with manufacturer in assembly, weather proof ratings, service access, and ventilation. Two major categories of cabinets are single enclosure or modular cabinet construction. Single enclosure cabinets use one structure to compose the entire LED display. A modular cabinet is a single enclosure cabinet that is A modular cabinet is a single enclosure cabinet that is designed to be connected to other cabinets, providing a method of building displays from installer standardized units. Depending on physical size, LED sign manufacturers use both single enclosure and modular cabinets.
Conformal coating material is applied to electronic circuitry to act as protection against moisture, dust, chemicals, and temperature extremes that if uncoated (non-protected) could result in a complete failure of the electronic system. Most circuit board assembly houses coat assemblies with a layer of transparent conformal coating rattier than potting.
Contrast Ratio is a measure of a display system, defined as the ratio of the luminance of the brightest color (white) to that of the darkest color (black) that the system is capable of producing. A high contrast ratio is a desired aspect of any display, but with the various methods of measurement for a system or its part, remarkably different measured values can sometimes produce similar results.
A controller is the main computer or “brain” of the LED display.
A feature of the control system that allows for monitoring and reporting of errors in the LED display in a readable report. Diagnostic levels will vary with manufacturer and may not be a feature of all control systems. Diagnostics may include monitoring of component temperatures, video signals, power supplies and in some cases even LED operation. Many manufacturers employ a diagnostic feature on all of their LED displays. This feature allows for quick and accurate troubleshooting if a problem occurs. The Display is queried while running and displays a report for each critical component.
Direct Inline Package – a LED that consists of two poles (one positive and one negative) through which electrical current runs to produce light. Poles are soldered to the computer chip separately.
A capability with the software that comes with some LED signs is the ability to “smooth” out pixelated graphics by allowing a pixel to “share” part of the pixels around itself, giving the graphics a better look. This technique is becoming less necessary now that higher definition signs are becoming more cost-effective.
Ethernet Cable Types & Terminologies
Category 5 (CAT5) – Category 5 cable is a twisted pair high signal integrity cable type often referred to as Cat5 or Cat-5. Most Category-5 cables are unshielded, relying on the twisted pair design for noise rejection. Category 5 has been superseded by the Category Se specification. This type of cable is used in structured cabling for computer networks such as Ethernet and ATM, and is used to carry many other signals such as telephony and video. CATS cable is limited to a 100 meter (300 ft.) distance.
Category 6 (CAT6) – Category 6 cable, commonly referred to as Cat.-6, is a cable standard for Gigabit Ethernet and other network protocols that are backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat.-5 and Cat.-5e, Cat.-6 features more stringent specifications for crosswalk and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T/1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet). Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a cable, or Augmented Category 6, is characterized to 500 MHz and has improved alien crosswalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols. Category 6 cable can be identified by the printing on the side of the cable sheath. CAT6 cable is limited to a 100 meter (300 ft.) distance.
Ultraviolet (UV) Shielded — This refers to the type of shielding employed to protect the cable from ultraviolet and electromagnetic interference. Most manufacturers utilize this type of for outdoor communication cable applications.
In electronics and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices. Typical examples of devices containing firmware range from end-user products such as remote controls to calculators. There are no strict boundaries between firmware and software, as both are quite loose descriptive terms. However, the term firmware was originally coined in order to contrast to higher-level software, which could be changed without replacing a hardware component, and firmware is typically involved with very basic low-level operations without which a device would be completely non-functional.
Frame rate, or frame frequency, is the frequency (rate) at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems. Frame rate is most often expressed in frames per second (FPS), (fps).
Full Color Display (RGB)
A display where the pixels are comprised of red, green and blue LEDs. The intensity of the LEDs can be controlled allowing the pixel to produce the full spectrum of colors. The number of colors varies with manufacturer, but ranges from 16.7 million to over 4 Quadrillion. Full Color displays are used to show text, images and videos and as prices have become more affordable, they have become the standard choice for many users. LED offers a full line of Full Color Displays capable of producing 281 Trillion Colors.
A grayscale display only shows shades of a certain color, usually red. Our grayscale displays show 4,096 shades, far exceeding the industry average.
A display where the pixels are comprised of single color LEDs, typically red or amber where the brightness of the individual pixels is controlled to create shading. Grayscale displays are used mainly for text applications, but offer smoother image quality due to the shading of the characters. Photo-realistic images and graphics can be displayed. The number of shades varies with manufacturer with offerings of 8, 16, 32, 64, 256, and 4,096 being typical specifications in the marketplace.
Ingress Protection (IP) Ratings
A specification of the environmental protection of electric enclosures and electrical equipment. The rating is comprised of two or three numbers.
1. Protection from solid objects or materials
2. Protection from liquids(water)
3. Protection against mechanical impacts(commonly omitted)
Most modern LED displays are rated IP65 or IP54.
A Light Emitting Diode (LED) is an electronic semiconductor that converts electric energy into visible light by releasing energy in an effect called electroluminescence. The color, brightness and power efficiency is determined by the elements used to compose the semiconductor. For electronic displays, the typical colors used are Red, Green, Blue and Amber, but LEDs are available across the visible, ultraviolet and infrared spectrums.
LEDs present many advantages over incandescent and fluorescent lighting sources including lower energy consumption, lower heat production, 100,000 Hour Life, smaller form factor, faster switching and greater reliability.
The lifespan of an LED is determined to be the point in which the brightness of the LED has degraded to 50% of the original value.
The LED cabinet is the metal enclosure that contains all of the LED display components. This critical structure protects the sensitive electronics inside from weather intrusion, debris and vandalism.
An LED module is a board that contains several rows and columns of pixels, as well as the circuitry and other electronics to power and control them. These modules are then configured edge-to-edge on a frame to form an LED display.
A device that detects the ambient light levels around the LED display, and adjust the display’s brightness accordingly. This prevents the sign from being too dim in the daytime, and too bright at night.
Master/Master and Master/Slave Configuration
On a two sided display, the sides can be configured to operate independently or together. In a master/master configuration, the two sides can either show the same message or can show different messages at the same time
Matrix/LED Matrix = Resolution
A measurement of how many pixels high (vertical) X how many pixels wide (horizontal) on a LED Sign
Max Viewing Angle
The most obtuse angle at which a sign is still viewable by the audience
A millicandela is a unit of measurement for the brightness of a single LED. A millicandela is equal to 1/1000 of a candela, which is comparable to a single candle’s brightness.
A LED Module is a combination of components that form the basic building blocks of the Electronic LED display. Modules are typically installed into a cabinet that houses the remainder of the components such as power supplies and other logic controls.
Modules will vary with manufacturer in both the components used to comprise the module, the size or shape, and the module matrix.
Measurement of light emitted by an LED display. One nit is equal to one candela per square meter.
A red LED display has 2 LEDs per pixel. A full color color display has 3 LEDs.
Pixel pitch = Definition: the distance from the center of one pixel to the center of its adjacent pixel.
The measurement from the center of one pixel to the adjacent pixel, either horizontal or vertical. Typically represented in millimeters. Pitch is used for a number of display related calculations including dimensions and character sizes.
The pixel dimensions of a display typically given in the format of pixels high by pixels wide.
Pixel stands for picture element. Pixels are light source points that illuminate together to form text and images. A pixel can be composed of a single LED or multiple LEDs of the same color (see Monochrome or Grayscale Displays) or multiple LEDs of different colors (see Tri-Color, Full Color / RGB). A pixel is the smallest element of an electronic display that is individually controlled.
A device that converts incoming AC power to the correct voltage DC power, and distributes it to electronic components. Several power supplies are typically required per LED display, with the number dependent on the size of the display. A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, for example AC power to DC power. A regulated power supply is one that controls the output voltage or current to a specific value; the controlled value is held nearly constant despite variations in either load current or the voltage supplied by the power supply’s energy source.
A device that takes input from a sender card, typically an Ethernet input, and converts it into a signal that is sent to the LED modules that make up a portion of the display.
Refresh Rate (Scan Rate)
The refresh rate is the number of times in a second that display hardware draws the data. 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 often a video source can feed an entire frame of new data to a display. For example, most movie projectors advance from one frame to the next one 24 times each second. However, each frame is illuminated two or three times before the next frame is projected using a shutter in front of its lamp. As a result, the movie projector runs at 24 frames per second, but has a 48 or 72 Hz refresh rate. Increasing the refresh rate decreases flickering, thereby reducing eyestrain.
The number of pixels in a defined area also another term to describe the matrix of a display, borrowed from the computer industry where printers and monitors have a resolution defined as the number of pixels in a defined area. This is somewhat ambiguous when describing image quality. A 16mm 64 x 64 LED display has the same resolution as a 32 mm 64 x 64 display, but the image quality will be affected by the distance the display is viewed from.
A device that takes input from the controller, typically from an HDMI or DVI input, and converts it into a signal that is sent to the receiver cards that make up a portion of the display.
SMD LED (Indoor and Outdoor)
The acronym for Surface Mount Diode. The diode(s) are mounted on a chipset and then mounted to the surface of a printed circuit board. Mainly for full color displays, Red, Green and Blue diodes can be housed on a single chipset. SMD LEDs typically have a 180-degree viewing angle and are popular for displays with pitches of lOmm or less. SMD LED technology is typically used for indoor displays but is starting to gain ground in the outdoor market for displays. Recent advances in the SMD technology has allowed for an Outdoor application although, it is important to note that this is very new technology and not proven over time to be effective.
A display where the pixels are comprised of red and green LEDs, typically providing nine colors ranging frorn Red, Green and Arnber. Popular for a ht period for outdoor use and more popular for indoor displays, tri-color displays typically do not employ any type of shading technology and have similar applications to a monochrome display.
Tri-color displays should not be confused with full color displays, as they can only show three distinct colors, not all the colors of the rainbow. This is considered an older technology and is rarely offered these days.
LEDs are brightest when viewed perpendicular to the emitting source and decrease in brightness as the viewing angle increases. The viewing angle is defined for both horizontal and vertical angles as the angle at which the intensity has dropped to 50. of the perpendicular brightness. The horizontal viewing angle is typically considered the more important of the two viewing angle specifications.
Viewing distances are calculated based on the display type and the intended audience for the display. Each display will have optimal minimum viewing distances that will vary based on application and use. The rule of thumb is to consider the minimum character height for the display and calculate based on 50′ of viewing distance for each inch. Example: a 20mm pitch LED hos a 5.5″ minimum character height. This can be viewed ot maximum of 250 ft.
The potential difference between two points of a conducting wire carrying a constant current of 1 ampere, when the power dissipated between these points is equal to 1 watt
(Measurement of Electric Volume) One watt is the rate at which work is done when one ampere of current flows through an electrical potential difference of one volt.