Sommario
Quick takeaway:
Visual effect, stability and energy consumption are the key points in usage of led display. And when we do the inspection, it can mainly divide into 5 categories.
1: Order information compliant with PI
2: Appearance Check before power up
3: Screen Splicing Check
4: Function Check after power up
5: Stability Check
Reference Documents:
SJ/T 11141-2017 Generic Specification for LED displays that issued by Ministry of Industry and Information Technology of the People’s Republic of China
SJ/T 11281-2017 Measure Methods of light emitting diode (LED) displays that issued by Ministry of Industry and Information Technology of the People’s Republic of China
GB/T 43770-2024 Specification for Indoor LED displays that issued by National Standardization Administration Committee of the People’s Republic of China
Order information compliant with PI
When you place a order, you would have a specs detail that offered by your supplier, Hence the first thing in inspect the led display is to check if the materials used in the order is compliant with the PI. Important components like LED lamps, ICs and Power suppliers not only affect the price of the led display a lot, but also affect the quality a lot.
For example, for same spec led display, the one with gold wire nationstar led lamp would cost double the price of the one with copper wire kinglight led lamp.
In this category, You also need to check about the control system, panel size, module size, Panel weight, Package style, and the spare parts qty, etc.
Appearance Check before power up
Appearance check before power up is mainly focus on appearance flaws, Such as
1: Scratches: Need to check the frame, modules, led boards, Mask, and other component surface
2: Burrs or Broken parts: Check the frame, modules, led boards to see if has Burrs, or broken parts
3: Missing or loosing Screws, Safety cables: Check if the screw is well screwed or missing. Does it have safety cable.
4: Labels: Check if has the right warning labels, brand labels
5: Panel’s color uniformity check ( Different batch mask would cause color difference)
Below you can see a picture with Burrs on the frame.
Screen Splicing Check
After we have done the basic appearance check, we can move to the splicing check. This is a important step that can determine the visual effect of the led display. The important check items are as below:
1: Splicing gaps check: the tolerance of the splicing gaps should be less than 5% of the pixel pitch. Which means if you ordered a pixel pitch 2.5mm screen, then the tolerance should be less than 0.125mm.
2: Splicing evenness check: the tolerance of the splicing evenness should be less than 5% of the pixel pitch. Which means if you ordered a pixel pitch 2.5mm screen, then the tolerance should be less than 0.125mm.
3:Screen color uniformity: Viewing from different angle to check if the the screen have different color blocks. (normally is caused by different batch mask, or different batch led lamp)
4: All electric socket integrity
5: Connection plate integrity and rigidity.
Below: you can see the color uniformity difference of different batch led mask
Function Check after power up
Function check is the most important check of all, as this determine the visual effect of the led display. Normally for the function check, we need to let the led display warm up first. All the function check need to be done after the led display has display white balance brightness for 15 minutes.
The reason is that, LED display would generate a lot of heat, and the led specs are not stable if the heat is not stable. Which would affect the brightness, CCT, greyscale and also the power consumption level.
For different kind of led display, it has different checking items, but it would be better that do the inspection based on the actual using environment. For example, for indoor led display, we can do the function check indoor, for outdoor led display we need to do the function check outdoor (not all panel)
In this checking category, we need to use the led display to display different types of videos, and images, and thought those videos and images, we can tell the visual effects of the led display. Most important items are
1: Display red, green, blue color to check if it is dead lamp
2: Display white color, checking the viewing angle and the color uniformity
3: Showing Slash line to check Ghost effect
4: Showing greyscale gradient bar, to check the gradient ability
5: Greyscale 0-255 auto changing to check the responsive
Stability Check
Stability check stimulates the led display’s quality under emergency conditions. Such as constant breakout, shake, water and fire, etc.
1: Power off test: turn on and turn off the power supplier of the led display for 3 times, then power on again to see if the led display still work properly.
2: Waterproof Checking : For different IP rating use different waterproof testing method. Only applicable for outdoor led display
3: Shaking testing: Put the led display on the shaking platform, then check if it still works properly
4: Fire Resistant testing: The plastic, rubber that used in led display should use fire resistant materials.
5: CE-LVD, CE-EMC, FCC, or other certificates requirements.
LED Display inspection checklist
| Inspection Item | Requirements | Result | Ruling | Remark | |||
| Order information compliant with PI | LED lamp brand | 口 Pass | 口 NG | ||||
| IC brand | 口 Pass | 口 NG | |||||
| Power supplier brand | 口 Pass | 口 NG | |||||
| Power Supplier Input voltage and Power plug type | 口 Pass | 口 NG | |||||
| Control system brand | 口 Pass | 口 NG | |||||
| Panel Size | 口 Pass | 口 NG | |||||
| Module Size | 口 Pass | 口 NG | |||||
| Panel Weight | 口 Pass | 口 NG | |||||
| Panel QTY | 口 Pass | 口 NG | |||||
| Package style | 口 Pass | 口 NG | |||||
| Spare parts QTY | 口 Pass | 口 NG | |||||
| Appearance Check before Power up | Module flatness within the panel(Torrenance < 5% * pitch pitch) | 口 Pass | 口 NG | ||||
| Module Gaps within the panel(tolerance< 5% * pitch pitch) | 口 Pass | 口 NG | |||||
| Panel color uniformity (Based on Viewing angle) | 口 Pass | 口 NG | |||||
| Scratches | 口 Pass | 口 NG | |||||
| Missing Screws, loosing Screws, Safty cable | 口 Pass | 口 NG | |||||
| Labels (Warning labels, brand labels) | 口 Pass | 口 NG | |||||
| Splicing Check | Connection Plate | 口 Pass | 口 NG | ||||
| Splicing gaps (tolerance < 5% * pitch pitch) | 口 Pass | 口 NG | |||||
| Splicing evenness (tolerance < 5% * pitch pitch) | 口 Pass | 口 NG | |||||
| Screen color Uniformity (Based on Viewing angle) | 口 Pass | 口 NG | |||||
| Power cable socket integrity | 口 Pass | 口 NG | |||||
| Signal cable socket integrity | 口 Pass | 口 NG | |||||
| Function Check after power up | Brightness (cd/m2) Measured after lightup for 15minutes | 口 Pass | 口 NG | ||||
| CCT (K) Measured after lightup for 15minutes | 口 Pass | 口 NG | |||||
| Color Coordinates, Measured after lightup for 15minutes | 口 Pass | 口 NG | |||||
| Viewing Angle (H/V) | 口 Pass | 口 NG | |||||
| Greyscale (bit) | 口 Pass | 口 NG | |||||
| Refresh Rate (Hz) | 口 Pass | 口 NG | |||||
| Dead lamp qty <1/10000 | 口 Pass | 口 NG | |||||
| Red color uniformity (100% / 70% / 30%) | 口 Pass | 口 NG | |||||
| Green color uniformity (100% / 70% / 30%) | 口 Pass | 口 NG | |||||
| Blue color uniformity (100% / 70% / 30%) | 口 Pass | 口 NG | |||||
| White color uniformity (100% / 70% / 30%) | 口 Pass | 口 NG | |||||
| Max wattage (w/sqm) | 口 Pass | 口 NG | |||||
| Showing slash line ( Ghost lamp effect) | 口 Pass | 口 NG | |||||
| Showing Greyscale gradient (uneven greyscale) | 口 Pass | 口 NG | |||||
| Grey scale 0-255 auto changing | 口 Pass | 口 NG | |||||
| Displaying high Contrast ratio video | 口 Pass | 口 NG | |||||
| Displaying Low greyscale video | 口 Pass | 口 NG | |||||
| Displaying Client’s video | 口 Pass | 口 NG | |||||
| Stability Checking | Power off test. Turn on and turn off the led displat 3 times to check if the led display still function normal | 口 Pass | 口 NG | ||||
| Waterproof Checking ( if applicable) | 口 Pass | 口 NG | |||||
| Shaking Testing | 口 Pass | 口 NG | |||||
| Fire Resistant Testing | 口 Pass | 口 NG | |||||
| CE, FCC, or other certificates check | 口 Pass | 口 NG | |||||
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