Issue Description: When thumb-sized black or gray patches, or dark shadows appear on the screen of your advertising display, building advertising screen, or commercial display panel, it not only disrupts the normal playback of content but may also indicate a hardware issue with the screen. This article provides a detailed analysis of the causes behind this phenomenon and offers practical solutions.
Part 1: Root Cause Analysis – Why Do Dark/Gray Spots Appear on Advertising Display Screens?
Fixed dark spots on the screen are typically not due to software issues or surface dirt but rather stem from physical changes within the LCD screen itself. The primary causes include:
Screen Dead Pixels (Mura Defect)
Cause: During the manufacturing process, uneven filling of liquid crystal materials, the intrusion of microscopic dust particles, or defects in optical films can lead to abnormal light transmittance in localized areas of the screen.
Manifestation: Irregular gray, dark, or color spots that remain fixed in position and visible across different solid-color backgrounds (e.g., white, red, blue).
Physical Pressure or Moisture Damage
Physical Pressure Damage: During transportation, installation, or daily cleaning, if the screen surface is subjected to pressure or impact from hard objects, permanent damage to internal components such as polarizers and light guide plates can occur. Even if the screen glass remains intact, visible patches may form internally.
Moisture/Dust Infiltration: If the device’s sealing is inadequate and it operates long-term in humid or dusty environments, moisture or dust can penetrate the screen interior, condensing or blocking light to form blurry gray or dark patches.
Part 2: Self-Diagnosis Steps – How to Preliminary Identify the Type of Dark Spot?
Before contacting technical support, you can perform the following steps for a preliminary assessment:
Basic Check: Gently wipe the screen surface with a soft microfiber cloth to confirm that the dark spot is not an external stain.
Screen Test: Display solid-color images (e.g., full white, full red, full blue) and observe whether the dark spot remains fixed across all colors. If yes, it is likely a physical screen issue.
Gentle Pressure Test (Caution: Proceed with Extreme Care):
With the device completely powered off, use your fingertip to very gently press the area of the dark spot.
If the spot’s appearance changes slightly under pressure, it is likely pressure damage.
If there is no change, it is more likely a dead pixel (Mura defect).
Part 3: Solutions and Professional Recommendations
Once physical damage is confirmed, it generally cannot be resolved through software or settings and requires professional intervention.
First Step: Contact Official After-Sales Service Immediately
We recommend reaching out to our official after-sales service team as soon as possible. To expedite the process, please prepare the following information in advance:
Device model and serial number (usually found on the body label).
Clear photos/videos of the issue.
Purchase date and description of the usage environment (e.g., humidity, dust levels).
Subsequent Process:
Within Warranty Period: After inspection by our engineers, if the issue is confirmed as non-user-induced quality problem, we will provide free screen repair or replacement.
Out of Warranty or User-Induced Damage: We will provide a detailed inspection report and transparent repair quotation. You can decide whether to proceed with the repair based on the device’s actual condition.
Part 4: Preventive Measures – How to Avoid Screen Dark Spot Issues?
Effective prevention can significantly extend the lifespan of your advertising display screen:
Proper Transportation and Installation: Ensure the screen surface is protected from pressure and impact during moving and installation.
Correct Cleaning Methods: Always power off the device before cleaning. Use dedicated screen cleaning cloths and solutions, and avoid harsh chemical liquids.
Optimize Operating Environment: Avoid installing the device in extremely humid, dusty, or environments with significant temperature fluctuations.
Summary
Dark or gray spots on advertising display screens primarily stem from physical damage. While they can affect visual quality, they can be resolved through professional diagnosis and repair. We are committed to providing reliable commercial display solutions and efficient technical support.
If you are experiencing issues such as "dark spots on advertising display screens," "gray spots on building advertising screens," or "shadows on commercial display panels," please do not hesitate to contact us for professional technical support and repair services.
"This article is part of the 'Advertising Machine FAQ' series. If you are experiencing other issues, such as unresponsive touch screens, black screens, etc., feel free to visit our [Advertising Machine Common Problems and Solutions (FAQ) Center | Ultimate Troubleshooting and Maintenance Guide] for quick answers."