Reasons and Solutions for LCD Flashing Phenomenon
Date:2025-06-10
The phenomenon of LCD screen flicker refers to abnormal display states such as abnormal brightness fluctuations, image shaking, or stripe interference on the screen. Its causes involve various factors such as hardware failures, driver abnormalities, and environmental interference. The following is a systematic analysis and solution:
1. Classification of Core Causes and Typical Cases
Backlight system malfunction
PWM dimming abnormality: When the LED backlight driving frequency is below 150Hz, the human eye can perceive periodic flickering (such as brightness flickering).
Backlight strip damage: Local LED failure resulting in regional flickering or uneven brightness.
Case: When HDR mode is turned on, the refresh rate is unstable and there are regular brightness fluctuations in the image.
Signal transmission issues
Connection line fault: Poor soldering of the wiring, oxidation of the interface, or interference with the LVDS signal,
causing image jitter/horizontal and vertical stripes.
Refresh rate mismatch: The difference between the screen refresh rate and the output frequency of the signal source
(such as conflicts between CPU write speed and module refresh rate).
Abnormal drive control
Timing control chip (TCON) failure: clock synchronization misalignment causing screen jumping or ghosting.
Liquid crystal polarization: The polarity of the driving voltage remains unchanged, causing brief flickering during
programming (which can damage liquid crystal molecules over time).
Environmental interference
Electromagnetic interference: The magnetic field generated by high-power equipment (motors, induction cookers)
causes the screen to flash in a "water ripple" pattern.
Voltage fluctuation: The filtering capacitor of the power adapter is damaged, causing unstable power supply and resulting
in brightness fluctuations.
Panel and hardware aging
LCD layer degradation: LCD leakage due to external impact or long-term use, resulting in unstable display.
TFT array damage: Local pixel driver failure, manifested as area flicker.
2. Key solutions and detection techniques
Hardware layer repair
Question type | Solution measures | Test method |
Backlight driver abnormality | Replace the constant current drive circuit to ensure that the PWM frequency is greater than 150Hz | Observation of Light and Dark Stripes in Slow Motion Photography with Mobile Phone |
Poor contact of the wiring harness | Re plug/solder FPC cable, apply anti oxidant to the interface | Gently shake the device to observe if the flashing screen intensifies |
Unstable power supply voltage | Install voltage regulator or UPS, replace bulging capacitor | Use a multimeter to detect voltage fluctuations in the circuit |
Driver and software tuning
Refresh rate setting: Adjust the system refresh rate to ≥ 75Hz to avoid frame rate tearing (such as Win11 turning off "automatic HDR" to solve compatibility flicker).
Initialization configuration: Strictly use the initialization code provided by the screen manufacturer (incorrect initialization leads to scrolling stripes on the screen).
Driver update: Upgrade graphics card/main control chip firmware, fix timing synchronization vulnerability.
Environmental adaptability design
Anti interference shielding: Add a magnetic ring to the signal line, and keep the display screen away from strong electromagnetic equipment by more than 50cm.
Heat dissipation optimization: Add heat sinks to TCON chips (stability increases by 7% for every 10 ℃ temperature drop).
3. Special scenario precautions
OLED screen low-frequency flicker: PWM dimming at low brightness can easily cause visual fatigue, and it is necessary to turn on "DC like dimming" and maintain brightness>40%.
Industrial equipment compatibility: SPI interface screens have weak anti-interference capabilities, and RGB/LVDS interface screens are preferred.
Flash screen of burning program: Initialize the pins or disconnect the screen cable before burning to avoid LCD polarization damage.
Diagnostic process mnemonic:
Check the line (connection), measure the source (power/signal), adjust the drive (driver), and avoid interference (environment). If there is still no solution, professional testing of the screen panel and main control chip is required.
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