The brightness of an LED electronic display screen can be determined using the following methods, while also considering the brightness standards for indoor and outdoor scenarios:
I. LED Electronic Display Screen Brightness Standards
Indoor Full-Color LED Display Screens: Brightness requirements are typically above 800 cd/m² to ensure clear image visibility under indoor lighting conditions.
Outdoor Full-Color LED Display Screens: Brightness requirements need to reach above 6000 cd/m² to cope with complex outdoor lighting conditions such as strong light and backlighting, avoiding image blurring.
II. Brightness Judgment Methods
1. Simple Light Measuring Device Construction and Use
Constructing a 3V DC Power Supply:
Use two button batteries connected in series, insert them into a small plastic tube, and lead out two probes as positive and negative outputs.
Use a spring-loaded switch at the end. When pressed, the positive and negative probes contact the LED pins, forming a power circuit.
Assembling a Photoresistor Light Measuring Device:
Connect thin wires to both ends of the photoresistor and connect them to the probes of a digital multimeter.
Set the multimeter to the 20KΩ range (adjust according to the photoresistor specifications to ensure accurate readings).
Principle: The stronger the light, the lower the resistance of the photoresistor, and the lower the multimeter reading; conversely, the stronger the light, the higher the resistance, and the higher the reading.
Measuring LED Brightness:
Light up a single LED with a 3V power supply, and place its light-emitting head directly against the photoresistor's photosensitive surface.
Record the multimeter reading. By comparing the readings of different LEDs, you can determine their brightness levels.
2. Professional Instrument Measurement (Recommended)
Using a luminance meter: Directly measures the brightness value (unit: cd/m2) of a specific area on the display screen surface, providing more accurate results.
Spectroradiometer: Analyzes the uniformity of brightness distribution, suitable for scenarios with high image quality requirements (such as stage backgrounds and billboards).
III. Precautions for Brightness Judgment
Ambient Light Interference: When measuring indoors, other light sources should be turned off to avoid ambient light affecting the reading; outdoor measurements should be taken on a sunny day at noon or at a time consistent with the lighting conditions of the usage scenario.
Measurement Point Selection: Evenly select multiple areas of the display screen (such as the center and four corners) for measurement, and calculate the average value to evaluate the overall brightness.
Dynamic Brightness Adjustment: Some displays support automatic brightness adjustment based on ambient light (e.g., intelligent light sensing). Measurement must be performed in standard mode to avoid errors.
IV. Other Relevant Screen Quality Indicators
1. Grayscale Levels
Definition: The number of brightness levels from blackest to whitest that the human eye can distinguish in an image.
Importance: Higher grayscale levels result in smoother color transitions and a larger color space.
Test Method: Use dedicated software (e.g., an LED tester) to display a grayscale gradient image and observe the number of levels that the human eye can distinguish.
High-quality displays typically have 256 or more grayscale levels, with some high-end products reaching 1024 levels.
2. Viewing Angle
Definition: The maximum range of angles from which the image remains clear and color accurate when viewed from different directions.
Standard: High-quality LED displays have a viewing angle of 160 degrees or more (horizontal/vertical).
Test Method: Observe the image from directly in front of the display and from the left and right sides, recording the angles at which color shift or brightness decay reaches 50%.
V. Summary
Core of Brightness Judgment: Measure the display screen brightness using a simple light meter or professional instrument, and compare it to indoor and outdoor standard values (800 cd/m² or above 6000 cd/m²).
Comprehensive Evaluation: Combine grayscale levels, viewing angles, and other indicators to comprehensively assess the display screen's quality and ensure it meets the needs of the usage scenario (such as advertising and information display).
Operational Recommendations: Non-professional users can prioritize using a luminance meter for quick measurements, or contact the manufacturer to obtain a test report to verify the accuracy of the parameters.
