As an important tool for modern media tool, LED display screens are widely used in subways, banks, hospitals, schools, shopping malls, hotels and other places. They not only provide rich information display functions such as text, images and videos, but also become the preferred display devices in many places due to their advantages such as high brightness, high contrast and long life.

However, how to ensure the quality and safety of LED display screens? You may need to pay attention to strict inspection standards and methods. SightLED will introduce the inspection standards and methods for indoor LED display screens in detail.

Appearance inspection of LED display screen

Appearance inspection is the first step of inspection. We can check the appearance quality of the LED display screen by visual inspection and simple tools.

LED Display screen component integrity

• The components of the LED screen should be complete, without missing or damage.
• The assembly should be firm, the structure should be stable, and there should be no looseness.
• The transition of edges and corners should be smooth, without defects such as flashing and burrs.

Casing and mounting connectors

• The casing and mounting connectors should have no obvious deformation, bumps and other defects.
• The color of the protective layer should be uniform, and there should be no defects such as exposed scratches and cracks.

Shell protection layer

The shell protection layer including the control box and connectors should be uniform in color, without scratches, cracks, etc.

The base should not have exposed parts to avoid the risk of electric shock.

LED display screen safety inspection

In addition, LED display screens that have passed safety inspections can be more reliable during use.

Grounding

• LED display screens should have protective grounding terminals
• The equipment can promptly conduct current to the ground when leakage occurs.
• The grounding resistance of a single LED display screen module should not exceed 0.1Ω.
• The metal shell of multiple spliced ​​LED display screens should be grounded together with the steel frame of the LED display screen, and the grounding resistance of the overall display system should not exceed 1Ω.

Safety marking

• The protective grounding terminal of the LED display screen should be clearly marked
• The marking should be firm and clearly legible.
• After the mark durability test, the mark should still be firm and clearly legible.
• There should be warning signs at the fuse and switch power supply
• It needs to undergo durability test.

Ground leakage current

The ground leakage current of the LED display should not exceed 3.5 mA/m² (effective value) to prevent the current leakage from causing harm to the user.

Dielectric strength

A test voltage of 50Hz basic sine wave and 1500V (effective value) is applied between the two poles of the power supply of the display module that constitutes the LED display, and between the two poles of the power supply and the protective ground. No insulation breakdown should occur during the test.

Temperature rise

When the LED display is in normal use, after reaching thermal equilibrium, the temperature rise of the metal part of the screen structure should not exceed 45K.

The temperature rise of the insulating material should not exceed 70K to prevent overheating and fire or damage to the equipment.

Energy saving inspection of LED display

In order to meet the need for less energy consumption, you also need to evaluate the energy efficiency of the LED display.

Average power efficiency

At room temperature, the power factor of the power supply of the LED display should not be less than 90%; the conversion rate should not be less than 70% to improve energy utilization efficiency.

Brightness adjustment

The outdoor LED display should have the function of automatically adjusting the brightness as the ambient brightness changes to reduce unnecessary energy consumption.

LED display structure inspection

In order to ensure the assembly accuracy and assembly quality of the display, you also need to conduct a LED display structure inspection.

Pixel center spacing

The nominal value of the pixel center spacing of the display should be retained to three decimal places to ensure accuracy.

LED Display module quality

The display module mass for non-fixed display screens should not exceed 36kg/m, which is convenient for installation and maintenance.

Assembly accuracy

After the assembly accuracy of the display screen is tested according to SJ/T 11281-2017, it should meet the requirements of the following table:

• Assembly gap width: not more than 1mm
• Assembly gap verticality: not more than 0.5mm
• Assembly gap parallelism: not more than 0.5mm

LED display light characteristic inspection

Light characteristic inspection is a key step in evaluating the display effect and visual quality of the display screen.

Maximum brightness

The maximum brightness of the display screen should meet the rated maximum brightness value requirements of the use environment

It can be clearly displayed under various lighting conditions.

Viewing angle

The horizontal viewing angle of the display screen should not be less than ±60°, and the vertical viewing angle should not be less than ±50°

Ensure that the audience can watch normally at different angles.

Brightness non-uniformity

The display screen should not have obvious bright or dark gaps, and the brightness non-uniformity should meet the specified standards

Ensure that the display screen is uniform.

Black screen non-uniformity

After the black screen non-uniformity test, the display screen should meet the specified standards

Ensure that there is no obvious brightness difference on the screen in the black screen state.

Chromaticity coordinates

The chromaticity coordinates of the three primary colors should be within the specified range to ensure accurate color reproduction.

The white field chromaticity coordinates of the color temperature point of the display screen calibrated within the rated color temperature range of the use environment should meet the tolerance of |△x|≤0.010, |△y|≤0.010 to ensure color consistency.

Brightness identification level

After the brightness identification level of the display screen is tested according to the requirements of SJ/T 11281-2017, it should not be less than 20 to ensure that the image details are clear and discernible.

Maximum contrast

When the illumination in the normal direction of the display screen is 10X(1±10%)1x, the maximum contrast should not be less than 1000:1, or should meet the nominal value to ensure that the image is clearly layered.

LED display electrical characteristics test

Electrical characteristics test is an important part of evaluating the electrical performance and display quality of the display.

Grayscale

After the grayscale level of the display screen is tested as required, it should not be less than 256 levels to ensure that the image is rich and delicate in color.

Frame change frequency

After the frame change frequency of the display screen is tested as required, it should comply with the regulations:

• The frame change frequency of the two-dimensional (2D) display screen should not be less than 50Hz;
• Ensure smooth images.
• The single-eye frame change frequency of the three-dimensional (3D) display screen should not be less than 50Hz;
• The binocular frame change frequency should not be less than 100Hz to ensure 3D display effects.

Visual refresh frequency

After the visual refresh frequency of the display screen is tested as required, it should comply with the regulations:

• The visual refresh frequency of the graphic display screen should not be less than 480Hz
• Ensure that the text image is clear and stable.
• The visual refresh frequency of the video display screen should not be less than 960Hz
• Ensure smooth video playback without stuttering.
• Pixel out-of-control rate
• The display screen should not have crosstalk or line defects
• Ensure that each pixel can be displayed normally.

Conclusion

We have introduced the inspection standards and methods for indoor LED display screens. Only after acceptance in multiple aspects such as appearance, safety, energy saving, structure, optical characteristics and electrical characteristics, can we ensure that the display screen meets the specified requirements in terms of quality, safety and energy efficiency.

In the inspection process, in addition to following the above standards and methods, you should also formulate a detailed inspection plan and process in combination with the specific product characteristics and usage environment. At the same time, the problems and defects found should be rectified and repaired in a timely manner.

With the continuous development of LED technology and the continuous expansion of application fields, the inspection standards and methods for indoor LED display screens will continue to be improved and updated. Therefore, relevant companies and personnel should pay close attention to industry trends and technological developments, continuously improve their own technical level and inspection capabilities, and provide users with more high-quality and reliable LED display products and services. If you want to find a trustworthy LED screen supplier, then don’t miss SightLED. We use strict standards as always, and you can be assured that every screen will be delivered to customers with high standards. If you need an LED screen, please feel free to contact us.