AMOLED Pixel Circuit Threshold Voltage Compensation and Touch Integration
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Solution Overview
Problem
The uniformity in brightness of AMOLED panels is compromised due to variations in threshold voltages of driving transistors, and integrating touch control circuits with pixel circuits is complex and costly, lacking a solution for perfect integration.
Innovation Solution
A pixel circuit design incorporating a compensating unit to pre-store threshold voltages and an insulating unit to isolate the driving transistor, along with a touch control circuit that multiplexes scan signals, allowing for stable driving current and seamless integration without added complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional 2T1C pixel circuit is used, then the circuit structure is simple, but the brightness uniformity is poor due to threshold voltage variations
Solution Approach 1:
The patent applies preliminary action by pre-storing the threshold voltage of the driving transistor in a capacitor during a compensation phase before the display phase. This allows the circuit to compensate for threshold voltage variations in advance, ensuring uniform brightness without adding excessive complexity to the overall circuit structure.
Solution Approach 2:
The patent introduces an insulating transistor as an intermediary element between the driving transistor and the OLED. This insulating transistor is controlled to be off during the compensation phase, preventing current leakage and enabling accurate threshold voltage compensation. The intermediary element resolves the contradiction by enabling compensation functionality without significantly increasing circuit complexity.
2Reliability
If display function and touch control function are manufactured separately and then fixed together, then each function can be optimized independently, but the process becomes complex and cost increases
Solution Approach 1:
The patent merges the display function and touch control function into a single integrated pixel circuit. The touch control transistor is integrated alongside the display circuit components (driving transistor, storage capacitor, insulating transistor), allowing both functions to be manufactured in the same process. This merging eliminates the need for separate manufacturing and assembly, reducing process complexity and cost while maintaining functionality.
Solution Approach 2:
The patent implements multi-functionality by designing the pixel circuit to perform both display and touch control functions. The insulating transistor serves dual purposes: it isolates the driving transistor during compensation phases for display functionality, and it enables touch sensing by controlling current paths during touch detection. This universal design allows a single circuit to fulfill multiple functions without requiring separate dedicated circuits.
Data Source
AI summary
A pixel circuit, a driving method for driving the pixel circuit and a display device comprising the pixel circuit. The pixel circuit insulates the electric connection between the drain of the driving transistor and the organic light-emitting diode by the insulating transistor when the data is written into the storage capacitor, and the threshold voltage of the driving transistor and the data voltage signal are pre-stored by the storage capacitor, which can compensate the shift in the threshold voltage effectively and in turn can ensure the uniformity and stabilization of the driving current. Additionally, the touch control circuit in the embodiments of the present disclosure multiplexes the scan signal of the pixel circuit, and the coupling capacitor in the touch control circuit is charged through the charging transistor while the storage capacitor is charged, therefore an integration of the touch control circuit into the pixel circuit is achieved perfectly.