What causes the display inversion anomaly in industrial LCD screens?
Date:2025-11-19
Abnormal inversion on industrial LCD screens is a common malfunction phenomenon. It typically manifests as a complete reversal of image colors or brightness levels, resembling a photographic negative.
The causes of this anomaly can primarily be attributed to three major categories: software/driver configuration issues, hardware connection problems, and faults in the screen or controller itself. Below, I will provide a detailed analysis and offer a troubleshooting approach.
Main Cause Analysis
I. Software and driver settings issues (the most common and easily solvable)
This is the most likely reason, usually related to the software or firmware configuration that drives the LCD screen. Polarity setting error: LCD screens require AC driving to prevent electrolyte polarization, which is achieved by periodically reversing the polarity of the driving voltage. If the timing or mode of this reversal (such as row reversal, column reversal, frame reversal, dot reversal) is not set correctly, it can cause display reversal on the entire screen or in certain areas.
Color format/data order mismatch: The pixel data format (such as RGB or BGR) sent by the main control board (driver board) does not match the default format received by the LCD screen. For example, if the main control outputs RGB, but the screen requires BGR, it will cause the red and blue channels to be swapped, resulting in color reversal.
Gamma correction or lookup table configuration error: The gamma correction curve or color lookup table inside the driver IC is incorrectly configured, causing the output grayscale or color relationship to be completely reversed.
Initialization code error: When powering on the screen, it is necessary to configure the registers of the driver IC through the initialization sequence. If a parameter in this sequence (such as scanning direction, color depth, driving mode) is set incorrectly, it can cause various display abnormalities, including inversion.
II. Hardware connection and signal issues
Physical connectivity issues can also lead to signal errors and cause display reversals.
Reverse LVDS line sequence: This is a very typical reason. The LVDS interface has strict positive and negative differential pair definitions. If the customized or used LVDS cable reverses the positive and negative poles of one or more pairs of differential lines, it may cause display reversal or color abnormalities.
Poor contact of connectors: FPC or LVDS connectors may experience poor contact due to vibration, oxidation, or other reasons, resulting in incorrect transmission of control or data signals.
Signal interference: The parallel wiring of screen lines and high-speed digital signal lines (such as clock and motor drive lines) without proper shielding can cause serious signal interference, which may lead to data confusion.
Power supply noise or unstable voltage: The quality of the power supply to the LCD screen or driver board is too poor, and the ripple noise is too large, which affects the normal operation of the driver IC or the integrity of the signal.
III. Screen or controller hardware failure (less likely but most severe)
If both of the above reasons are ruled out, it may be due to hardware damage itself.
LCD screen driver IC malfunction: The internal driver integrated circuit of the screen is partially damaged and cannot correctly interpret signals from the main control.
Mainboard Timing Controller Failure: For large-sized LCD screens, the internal T-Con board is responsible for receiving signals and controlling source and gate drivers. If the T-Con board fails, it can cause global display abnormalities.
Screen line or binding process issues: The COF/COG process connecting the glass substrate and PCB driver board may experience slight damage after long-term use or mechanical stress, resulting in abnormal signal transmission.
Problem troubleshooting ideas and steps (from simple to complex)
When encountering display reversal anomalies, it is recommended to follow the following steps for troubleshooting:
1. Priority for software troubleshooting:
Check the driver configuration: First, confirm whether the color format (RGB/BGR), scanning direction, driver polarity, and other settings in your driver board program or initialization code are correct. It is best to check each item against the recommended parameters in the LCD screen specification book.
Update/Refresh Firmware: Attempt to update the firmware of the main control board or driver board, sometimes it may be a bug in the firmware itself.
Replacement method verification: Use a known normal driver board compatible with your screen model (such as the driver board provided by Xuhong Technology) to light up the screen. If the display is normal, the problem must be with your original driver board or software configuration.
2. Check hardware connections:
Re plug and unplug cables: Turn off the power, re plug and unplug all connectors such as LVDS cables and FPC cables to ensure good contact.
Check cables: Confirm that the line sequence definition of the LVDS cable or FPC ribbon used is completely consistent with the requirements of your LCD screen and driver board. If you have customized special wires for Xuhong Technology, please check the drawings with us.
Attempt to replace cable: Use a confirmed good cable of the same model for replacement testing.
3. Check the working environment:
Measure power supply: Use an oscilloscope to check whether the power supply voltage to the driver board and LCD screen is stable and whether the ripple is within the allowable range.
Check grounding and shielding: Ensure good system grounding and keep signal lines away from noise sources.
4. Final judgment:
If the problem persists after replacing the driver board and cables through all the above steps, and tests on another screen of the same model are normal, it is likely that the driver IC or T-Con board of the LCD screen itself has malfunctioned. At this point, it is necessary to contact the supplier for factory inspection or replacement.
Summary
Investigation level | Possible reasons | Troubleshooting method |
high | Software/driver configuration error | Verify specifications, check initialization code, replace driver board for testing |
medium | Hardware connection issues (line sequence/contact) | Re plug, replace cables, and verify the definition of cable sequence |
low | Screen or controller hardware malfunction | Replacement method (test with new screen), return to factory for inspection |
As a user of Xuhong Technology, your advantage lies in:
When you purchase LCD screens from us and provide corresponding driver solutions, we offer not only screens, but also a one-stop solution of "screen+driver board" that has been rigorously tested and matched. This greatly reduces the risk of such problems caused by software and hardware mismatches. Once a problem occurs, our technical support team can quickly locate whether it is a screen issue or a driver issue, and provide corresponding initialization code references to help you efficiently solve the problem.
If you encounter difficulties in troubleshooting, please feel free to contact us and provide specific LCD screen models and driver board information. We will be dedicated to providing you with technical support.
AUO LCD Display：https://www.auo-lcd.com/products/auo-lcd-screen/
