LCD Leakage Compensation via Timing Controller Charging Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The longer vertical blank interval at low refresh frequencies in LCDs leads to increased leakage and flicker issues due to the need for longer voltage maintenance, causing luminance differences between low and high refresh frequencies.
Innovation Solution
A leakage compensation mechanism that uses a timing controller to adjust the current refresh frequency and increase the charging time of TFTs when the refresh frequency is lower than a threshold, without modifying the LCD circuit design, by transferring a control signal to the gate driver to extend the charging time of TFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refresh frequency is reduced to improve display smoothness and enable Freesync functionality, then the vertical blank interval increases causing longer voltage maintenance time, but this leads to increased current leakage and luminance inconsistency
Solution Approach 1:
The patent applies preliminary action by extending the charging time of TFTs before the vertical blank interval begins. The timing controller adjusts the gate driver to provide a longer charging period at low refresh frequencies, ensuring that TFTs are fully charged before the extended maintenance period starts, thereby compensating for the increased leakage during the longer vertical blank interval
Solution Approach 2:
The patent implements dynamics by making the charging time variable rather than fixed. The timing controller dynamically adjusts the charging time based on the refresh frequency - using a first charging time at high refresh frequencies and a second, longer charging time at low refresh frequencies. This dynamic adjustment optimizes performance across different operating conditions while maintaining luminance consistency
2Productivity
If the vertical blank interval is extended at low refresh frequencies, then the display can maintain lower refresh rates for smoothness, but the luminance difference between low and high refresh frequencies increases due to leakage
Solution Approach 1:
The patent applies parameter changes by modifying the charging time parameter based on refresh frequency conditions. The timing controller detects the refresh frequency and adjusts the charging time parameter accordingly - using a first charging time parameter at high refresh frequencies and a second, extended charging time parameter at low refresh frequencies. This parameter adjustment compensates for leakage effects and maintains luminance consistency across different refresh rates
3Manufacturing precision
If the charging time is increased to compensate for leakage at low refresh frequencies, then luminance consistency is maintained, but the circuit design complexity increases
Solution Approach 1:
The patent applies universality by making the timing controller perform multiple functions - it not only generates timing signals for the gate and source drivers but also dynamically adjusts the charging time based on refresh frequency detection. This multi-functionality allows the system to maintain luminance consistency across different refresh rates without adding separate dedicated compensation circuitry, thereby avoiding increased device complexity
Data Source
AI summary
A liquid crystal display (LCD) and a method for compensating current leakage of the LCD are provided. The LCD includes a thin film transistor (TFT) array having a plurality of TFTs, a gate driver configured to provide a scan signal, a source driver configured to provide a data signal, and a timing controller electrically connected to the gate driver and the source driver. The timing controller is configured to adjust a current refresh frequency according to a current frame rate and to transfer a control signal to the gate driver when the current refresh frequency is lower than a threshold frequency such that the gate driver increase a charging time of the plurality of TFTs according to the control signal.