Display Compensation Circuit for Long Horizontal Blank Brightness Artifacts
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Solution Overview
Problem
Touchscreen displays experience brightness artifacts due to charge leakage during long horizontal blank periods, which affect the accuracy of proximity sensing and user interaction.
Innovation Solution
A compensation circuit is introduced to adjust display data values, such as gamma voltage and gate clock width, to compensate for brightness artifacts by mapping compensation amounts based on temperature and LHB length, ensuring accurate proximity sensing and improved user interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensing is performed during blank periods to improve proximity sensing accuracy, then measurement precision is improved, but brightness artifacts occur due to charge leakage during long horizontal blank periods
Solution Approach 1:
The compensation circuit performs preliminary compensation by adjusting display data values before the long horizontal blank period occurs. The circuit proactively modifies gamma voltages and gate clock widths for rows that will be affected by the extended blank period, preventing brightness artifacts from occurring in the first place rather than correcting them afterward.
Solution Approach 2:
The compensation circuit changes display parameters dynamically based on the presence of long horizontal blank periods. Specifically, it adjusts gamma voltage values and gate clock widths for affected rows, modifying these parameters in response to the extended blank period conditions to maintain uniform display brightness and prevent charge leakage artifacts.
2Measurement precision
If display updating is paused during blank periods for proximity sensing, then measurement precision is improved, but display brightness stability deteriorates due to charge leakage
Solution Approach 1:
The compensation circuit performs preliminary compensation by adjusting display data values before the long horizontal blank period occurs. The circuit proactively modifies gamma voltages and gate clock widths for rows that will be affected by the extended blank period, preventing brightness artifacts from occurring in the first place rather than correcting them afterward.
Solution Approach 2:
The compensation circuit implements a feedback mechanism where the display driver monitors for the presence of long horizontal blank periods and automatically activates compensation adjustments. The compensation register stores mapping information that guides the compensation circuit in determining appropriate adjustments, creating a closed-loop system that maintains brightness stability despite extended blank periods.
3Stability of the object's composition
If gamma voltage and gate clock width are adjusted to compensate for brightness artifacts, then brightness stability is improved, but device complexity increases due to the compensation circuit
Solution Approach 1:
The compensation circuit is integrated into the existing display driver architecture, allowing the same hardware components to serve multiple functions. The compensation register and circuitry work alongside the normal display updating circuitry, enabling the system to perform both standard display operations and brightness compensation without requiring entirely separate dedicated components.
Solution Approach 2:
The compensation circuit operates autonomously within the display driver, automatically detecting when long horizontal blank periods occur and applying appropriate compensations without requiring external intervention. The compensation register contains pre-stored mapping information that guides the circuit's adjustments, enabling self-service operation that minimizes the need for additional control logic.
Data Source
AI summary
One or more embodiments are directed to compensating for a long horizontal blank (LHB) period. Using a first display data value, a compensation amount is determined from a mapping between display data and compensation amounts. The first display data value is for a display row after an LHB period in a display frame of a display panel. A second display data value is adjusted with the compensation amount to obtain revised display data value. The revised display data value is outputted for the display panel.