Basic Knowledge of LED Modules (Part 3)
Product Terminology
What is LED:
LED stands for Light Emitting Diode. In the display screen industry, “LED” specifically refers to LEDs that emit visible light.
What is a Pixel:
The smallest light-emitting unit of an LED display, equivalent to the term “pixel” in standard computer monitors.
What is Pixel Pitch (Dot Pitch):
The center-to-center distance between two adjacent pixels.
What is an LED Display Module:
A structurally independent unit composed of multiple display pixels, serving as the smallest building block of an LED display.
What is DIP:
DIP stands for Double In-line Package, a dual-row pin insertion assembly method.
What are SMT and SMD:
- SMT (Surface Mounted Technology): The most widely used technology and process in the electronics assembly industry.
- SMD (Surface Mounted Device): A component designed for surface mounting.
What is an LED Display Module:
A functional unit with predefined circuitry and mounting structure, capable of forming an LED display through simple assembly.
What is an LED Display:
A display screen composed of an array of LED devices controlled via specific methods.
What is a DIP Module? Its Pros and Cons:
A module where DIP-packaged LEDs are inserted into PCB holes and soldered.
- Pros: High brightness, excellent heat dissipation.
- Cons: Low pixel density.
What is an SMT Module? Its Pros and Cons:
A module where SMD LEDs are soldered directly onto the PCB surface.
- Pros: Superior display quality, high pixel density, ideal for indoor use.
- Cons: Lower brightness, poor heat dissipation.
What is a Sub-SMT Module? Its Pros and Cons:
A hybrid between DIP and SMT. LEDs have surface-mounted packaging but are inserted through the PCB for soldering.
- Pros: High brightness, good display quality.
- Cons: Complex manufacturing, difficult repairs.
What is 3-in-1? Its Pros and Cons:
RGB LED chips are vertically packaged into a single SMT lamp.
- Pros: Excellent color mixing, stable performance.
- Cons: Complex process, difficult repairs.
What is 3-in-Line? Its Pros and Cons:
Three independently packaged RGB SMD LEDs arranged vertically.
- Pros: Simpler manufacturing, easier repairs.
- Cons: Inferior color mixing and stability compared to 3-in-1.
What is Luminance:
The light intensity emitted per unit area of an LED display, measured in cd/m² (candelas per square meter).
What is Brightness Level:
The number of adjustable brightness levels from minimum to maximum.
What is Grayscale Level:
The number of gradation steps between the darkest and brightest states at a fixed brightness level.
What is White Balance and White Balance Adjustment:
- White Balance: The balance of brightness ratios among RGB LEDs to produce pure white.
- White Balance Adjustment: Calibrating RGB brightness ratios and white coordinates.
What is Contrast Ratio:
The ratio of maximum brightness to background brightness under specific ambient lighting.
What is Color Temperature:
The temperature of a blackbody radiator that emits light matching the color of a light source, measured in Kelvin (K).
What is Frame Refresh Rate:
The frequency at which the display updates its content per unit time.
What is Refresh Rate:
The frequency at which the display redraws the image per unit time.
What are Viewing Angle, Effective Viewing Angle, and Optimal Viewing Angle?
- Viewing Angle: The angle at which brightness drops to half of the frontal (normal) brightness, measured horizontally and vertically.
- Effective Viewing Angle: The maximum angle where the display content remains visible.
- Optimal Viewing Angle: The angle where colors and image clarity are best preserved.
What is Optimal Viewing Distance:
The distance from the screen where the display content is fully visible without color distortion and with maximum clarity.
What are Static Drive and Scan Drive? Differences:
- Static Drive: Direct “point-to-point” control from the driver IC to pixels. No row control circuit required.
- Pros: High stability, minimal brightness loss.
- Cons: Higher cost.
- Scan Drive: “Point-to-column” control requiring row control circuits.
- Pros: Lower cost.
- Cons: Reduced brightness, lower stability.
What are Constant Current Drive and Constant Voltage Drive?
- Constant Current Drive: Maintains a fixed output current within the driver IC’s operating range.
- Constant Voltage Drive: Maintains a fixed output voltage within the driver IC’s operating range.
What are Synchronous and Asynchronous Systems?
- Synchronous System: The LED display content updates in real-time synchronization with a connected computer.
- Asynchronous System: Preloaded content is stored in the display’s control system, allowing operation without a connected computer.
What is Fiber Optic Transmission vs. Network Cable Transmission?
- Fiber Optic: Converts electrical signals to light for transmission via glass fibers.
- Network Cable: Transmits electrical signals directly through metal wires.
When to Use Network Cable vs. Fiber Optic?
- Network Cable: For distances under 100 meters.
- Multimode Fiber: For distances between 100–500 meters.
- Single-mode Fiber: For distances over 500 meters.
What are LAN Control and Internet Control?
- LAN Control: Local network-based control of devices within the same network.
- Internet Control: Remote control via the internet using IP addresses.
