Explanation of LED Technical Terms

Author: Huajiang

Date: 2023-09-08 11:55:59

When purchasing LED displays, I don't understand the professional terminology that others are using. Below are explanations of LED display terms.

LED (Light Emitting Diode): LED is the abbreviation for "Light Emitting Diode." In the LED display industry, LED specifically refers to LEDs that emit visible wavelengths.

Pixel: A pixel is the smallest illuminated unit on an LED display, and its meaning is similar to that of pixels in a regular computer monitor.

Pixel Pitch: The center-to-center distance between adjacent pixel points. A smaller pitch results in a shorter viewing distance. It is commonly denoted as "P" in the industry.

Pixel Density: Also known as dot matrix density, it typically refers to the number of pixels per square meter on the display screen.

LED Module (Panel): A minimal unit that consists of several display pixels and is structurally independent. It forms the smallest building block of an LED display screen. Examples include 8x8 and 8x7 modules, which are basic units with display functionality, circuitry, and installation structures that can be easily assembled to create a display screen.

DIP (Double In-Line Package): DIP is an abbreviation for Double In-Line Package, which refers to a type of packaging used for electronic components in a dual-row, straight-pin configuration.

SMD/SMT: SMT stands for Surface Mounted Technology, which is the most popular technology and process in the electronics assembly industry. SMD stands for Surface Mounted Device.

LED Display Screen: A display screen composed of an array of LED devices controlled in a certain way.

Through-Hole (DIP): Through-hole, or DIP, refers to the process of passing the pins of DIP-packaged components through a PCB board and soldering them to fill the holes with solder. Advantages include high brightness and good heat dissipation, but it has a lower pixel density.

Surface Mount Module: Surface mount modules, also known as SMT (Surface Mount Technology) modules, involve soldering SMT-packaged LEDs onto the surface of a PCB without passing the LED pins through the board. Advantages include good display quality and high pixel density, suitable for indoor viewing, but they may have lower brightness and less efficient heat dissipation.

3-in-1: 3-in-1 refers to vertically aligning RGB LEDs, each with a different color, at a specific spacing. This approach combines the advantages of 3-in-1 while addressing its disadvantages, such as complex manufacturing and repair difficulties.

3-and-1: 3-and-1 involves vertically aligning independently packaged RGB SMT LEDs at a specific spacing, offering the advantages of 3-in-1 while addressing its disadvantages.

Dual Color, Pseudo-Color, Full Color Display: These terms refer to different types of displays created using LEDs of different colors. Dual color consists of two colors, typically red and green or amber-green. Pseudo-color displays use three different colors, usually red, amber-green, and blue, while full-color displays use three distinct colors: red, pure green, and pure blue.

Luminous Brightness: The intensity of light emitted per unit area of an LED display screen, measured in CD/square meter. In simple terms, it represents the brightness emitted by the display per square meter.

Brightness Level: The number of manually or automatically adjustable levels between the lowest and highest brightness of the entire screen.

Gray Level: The technical processing levels between the darkest and brightest states of an LED display screen at the same brightness level. Gray levels can be described in various ways.

Maximum Brightness: The maximum brightness and maximum gray level of each color component of an LED display screen under specific ambient lighting conditions.

Moire Pattern: In the context of capturing images or videos of full-color LED display screens, irregular water-like patterns that appear on the LED screen are known as "moire patterns" in physics.

PCB Board: PCB stands for Printed Circuit Board, which is a board used to mechanically support and electrically connect electronic components using conductive pathways, tracks, or traces etched from copper sheets.

Module (Panel) Dimensions: Refers to the size of the module or panel, typically expressed in millimeters as the length multiplied by the width (e.g., 48x244).

Module (Panel) Resolution: Refers to how many pixels are on a single module or panel, typically expressed as the number of rows multiplied by the number of columns (e.g., 64x32).

BOM (Bill of Materials): A list that itemizes all the materials, components, and parts needed to manufacture a product.

White Balance and White Balance Adjustment: White balance refers to the balance of white, specifically the balance of the brightness ratios of the RGB (Red, Green, Blue) colors. Adjusting the brightness ratios of RGB colors and the coordinates of white is called white balance adjustment.

Contrast Ratio: The ratio between the maximum brightness of an LED display screen and the background brightness under specific ambient lighting conditions.

Color Temperature: The color emitted by a light source when its color matches the color of a black body radiator at a specific temperature. This temperature is referred to as the color temperature of the light source.

Color Deviation: LED display screens produce various colors by combining red, green, and blue colors. However, these three colors are made from different materials and have different viewing angles. The observable differences in color due to variations in the spectral distribution of different LEDs are referred to as color deviation. When viewing LEDs at certain angles, their colors may change, and the human eye's ability to judge the true colors of an image (e.g., in movies) is often better than when viewing computer-generated images.

Frame Rate: The number of times the information on an LED display screen is updated within a unit of time. It involves dividing the displayed content into multiple segments for playback. Frame rates are typically around 60 frames per second, and they are nearly imperceptible to the human eye.

Refresh Rate: The number of times an LED display screen repeats the display of its content within a unit of time. A higher refresh rate results in smoother and more detailed images.

Viewing Angle, Viewing Cone, and Optimal Viewing Angle:

•   Viewing Angle: The angle at which the brightness in the observation direction decreases to half the brightness perpendicular to the LED display screen's normal.
• Viewing Cone: The angle between two observation directions in the same plane and the normal direction to the screen. It includes both horizontal and vertical viewing angles.
• Optimal Viewing Angle: The angle at which the content on the display screen can be seen perfectly without color distortion, and the image is clearest. It is the angle between the normal direction and the direction of optimal viewing.

Optimal Viewing Distance: The vertical distance relative to the screen where the content on the display screen can be seen perfectly without color distortion, and the image is clearest.

Defective Pixels and Types: Pixels that do not meet the desired emission or control requirements are considered defective pixels. There are three types of defective pixels:

• Dead Pixels (Stuck Pixels): Pixels that remain unlit and do not change.
• Bright Pixels: Pixels that remain lit continuously.
• Flashing Pixels: Pixels that exhibit erratic flickering.

Static Driving vs. Scanning Driving and Their Differences:

• Static Driving: In static driving, each pixel on the LED display screen is controlled directly from the output pins of the driving IC. It is a one-to-one control method. Static driving is costlier but offers better display quality, stability, and minimal brightness loss.
• Scanning Driving: In scanning driving, the control is done on a column-by-column basis. It requires a row control circuit. Scanning driving is cost-effective but may result in lower display quality, higher brightness loss, and other drawbacks.

Constant Current Drive vs. Constant Voltage Drive:

• Constant Current: It refers to maintaining a constant current value within the allowed working environment specified by the driving IC.
• Constant Voltage: It refers to maintaining a constant voltage value within the allowed working environment specified by the driving IC.

Aspect Ratio of LED Display Screens:

• Text and Graphics Screens: Determined based on the displayed content.
• Video Screens: Typically 4:3 or close to 4:3. The ideal ratio is 16:9.

Number of Pixels Controlled by a Control System:

• Communication Screen A Card: Single-color and dual-color: 1024x64 pixels.
• Communication Screen B Card: Single-color: 896x512 pixels, Dual-color: 896x256 pixels.
• DVI Dual-color Screen: 1280x768 pixels.
• DVI Full-color Screen: 1024x512 pixels.

Nonlinear Correction:

When the digital signal output by a computer is displayed on an LED display screen without correction, color distortion can occur. Nonlinear correction involves processing the computer's original output signal through a nonlinear function to obtain the signal required by the display screen. This correction is necessary because the relationship between the input and output signals is nonlinear.

Rated Operating Voltage, Operating Voltage, and Supply Voltage:

• Rated Operating Voltage: The voltage at which an electrical device is designed to operate normally.
• Operating Voltage: The voltage at which an electrical device operates within the specified voltage range while functioning normally.
• Supply Voltage: The voltage supplied to the device, which can be either AC or DC. AC supply voltage typically ranges from 220V to 240V, while DC supply voltage is often 5VDC or 12VDC, with solar power systems typically using 12V.

Color Distortion:

Color distortion occurs when the same object is viewed in the natural world and on a display screen, resulting in differences in how they are perceived by the human eye.

Synchronous System vs. Asynchronous System:

• Synchronous System: In a synchronous system, the content displayed on the LED display screen is synchronized with the computer monitor through a control system.
• Asynchronous System: In an asynchronous system, the display data edited on a computer is stored in the display screen control system in advance. The computer can be turned off without affecting the normal display of the LED screen.

Blind Spot Detection Technology:

Blind spot detection technology involves using upper-level software and lower-level hardware to detect blind spots on the display screen (such as LED open circuits and short circuits). It generates reports to inform LED screen administrators of these issues.

Power Supply Detection: Power supply detection is a technology that uses upper-level software and lower-level hardware to detect the operating status of various power supplies on the display screen. It generates reports to inform LED screen administrators of this information.

Brightness Detection and Brightness Adjustment:

•   Brightness in Brightness Detection: In brightness detection, brightness refers to the ambient brightness in which the LED display screen is located. Light sensors are used to measure the current ambient brightness, and this method is known as brightness detection.
• Brightness in Brightness Adjustment: In brightness adjustment, brightness refers to the brightness emitted by the LED display screen itself. The detected data is fed back to the LED display screen control system or control computer, which then adjusts the screen's brightness.

Real Pixels vs. Virtual Pixels and Types of Virtual Pixels:

•   Real Pixels: Physical pixels on an LED display screen where there is a 1:1 relationship between the number of physical pixels and the number of displayed pixels.
• Virtual Pixels: Virtual pixels refer to the situation where the number of physical pixels and the number of displayed pixels have a 1:N (N=2, 4) relationship. Virtual pixels can display a pixel count that is 2 or 4 times greater than the actual physical pixel count. Virtual pixels can be categorized as follows:
• Software Virtual and Hardware Virtual: Depending on whether the virtualization is achieved through software or hardware.
• 2x Virtual and 4x Virtual: Based on the level of virtualization.
• 1R1G1B Virtual and 2R1G1B Virtual: Based on the arrangement of LEDs on a module.

Remote Control and When to Use It:

Remote control doesn't necessarily mean long-distance control. It can involve both the main control and the controlled device being in the same local network, which may not be physically far apart. Remote control is used in situations where clients request or require control from a location beyond the direct control of the LED display.

Fiber Optic Transmission vs. Ethernet Transmission:

• Fiber Optic Transmission: It involves converting electrical signals into optical signals and transmitting them through transparent glass fibers.
• Ethernet Transmission: It involves direct transmission of electrical signals through metal conductors (copper wires) for data communication.

When to Use Ethernet vs. Fiber Optic Transmission:

• Ethernet is used when the distance between the display screen and the control computer is less than 100 meters.
• Multimode optical fiber is used when the distance is greater than 100 meters but less than 500 meters.
• Single-mode optical fiber is used when the distance is greater than 500 meters.

Local Area Network (LAN) Control vs. Internet Control:

• LAN Control: In LAN control, one computer controls another computer or connects to external devices within the same local network.
• Internet Control: Internet control involves controlling a device remotely over the internet, using the IP address of the controlled device in the internet network.

DVI vs. VGA:

•   DVI (Digital Video Interface): DVI is a digital video interface used for transmitting digital video signals. It is an international standard for digital video interfaces.
• VGA (Video Graphics Array): VGA is an older standard introduced by IBM in 1987 for computer displays. It uses analog signals for video transmission.

Digital Signal and Digital Circuit:

• Digital Signal: A digital signal is one in which the amplitude values are discrete, typically limited to two finite values, often represented as 0 and 1. Digital signals are processed and controlled by digital circuits.
• Digital Circuit: A digital circuit is an electronic circuit that processes digital signals. It operates based on binary logic, where signals represent discrete values (usually 0 or 1). Digital circuits are commonly used in computers and other digital electronics.

Analog Signal and Analog Circuit:

• Analog Signal: An analog signal is one in which the amplitude values vary continuously over time. Unlike digital signals, analog signals have a continuous range of values. Analog circuits process and control these continuous signals.
• Analog Circuit: An analog circuit is an electronic circuit that processes analog signals. It deals with continuous voltage or current levels and is used in applications where the signal is not naturally discrete.

PCI Slot (Peripheral Component Interconnect Slot):

PCI slots are expansion slots on a computer motherboard designed for connecting various types of expansion cards or peripherals. They are based on the PCI local bus standard and are a primary means of adding functionality to a computer by plugging in different expansion cards.

AGP Slot (Accelerated Graphics Port Slot):

AGP is an interface specification designed for faster and smoother rendering of 3D graphics on personal computers. AGP uses a dedicated port for graphics processing and leverages the computer's main memory for refreshing the display at higher speeds. It supports 3D graphics technologies like texture mapping, zero buffering, and alpha blending.

GPRS, GSM, and CDMA:

•   GPRS (General Packet Radio Service): GPRS is a packet-switched wireless communication service that evolved from the existing GSM (Global System for Mobile Communications) system. It is primarily used for data transmission over mobile networks.
• GSM (Global System for Mobile Communications): GSM is a standard for digital cellular networks developed in 1992 by the European Telecommunications Standards Institute (ETSI). It is a widely adopted technology for mobile communication.
• CDMA (Code Division Multiple Access): CDMA is a digital cellular technology that allows multiple users to share the same frequency spectrum simultaneously. It's an alternative to GSM and is used by some mobile carriers around the world.