OLED Sensing Circuit with Amplifier Correction for Aging Compensation
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Solution Overview
Problem
Large-sized organic light-emitting diode (OLED) display apparatuses face challenges in sensing transistors or light emitting devices due to high resistance and parasitic capacitance in pixel circuits, leading to suboptimal display performance.
Innovation Solution
A sensing circuit comprising an operation amplifier, integration capacitor, and switch configurations that allow for correction of the operation amplifier and integration capacitor, along with an analog-to-digital converter, to accurately sense and correct parameters like threshold voltage, mobility, and luminous efficiency of the light emitting unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external sensing method is used for compensation, then the transistor aging can be compensated, but the sensing precision is insufficient due to high resistance and parasitic capacitance in large-sized OLED pixel circuits
Solution Approach 1:
The patent introduces a dedicated sensing circuit as an intermediary component between the pixel circuit and the compensation system. This sensing circuit includes a sensing transistor, sensing capacitor, and sensing line that are specifically designed to interface with the pixel circuit without being affected by the high resistance and parasitic capacitance issues. The sensing circuit acts as a mediator that accurately captures the threshold voltage and mobility parameters of the driving transistor, enabling precise compensation despite the challenging electrical characteristics of large-sized OLED pixel circuits.
Solution Approach 2:
The patent segments the sensing function from the general pixel circuit operation by creating a separate, dedicated sensing circuit path. This segmentation allows the sensing operation to be performed independently with optimized components (sensing transistor, sensing capacitor, sensing line) that are not subject to the same performance limitations as the main pixel circuit. The segmented approach enables accurate parameter measurement even when the overall pixel circuit exhibits high resistance and parasitic capacitance.
2Device complexity
If the sensing circuit parameters are not corrected, then the circuit operation is simple, but the sensing accuracy is affected by operation amplifier offset voltage and integration capacitor leakage current
Solution Approach 1:
The patent implements preliminary correction actions by introducing correction circuits that compensate for operation amplifier offset voltage and integration capacitor leakage current before these errors affect the sensing measurement. The correction mechanism pre-adjusts the sensing circuit parameters to counteract the expected errors, ensuring that the final sensing accuracy is not degraded by these inherent circuit imperfections. This preliminary correction approach maintains sensing precision without significantly complicating the overall circuit operation.
Solution Approach 2:
The patent employs feedback mechanisms where the sensing circuit parameters are continuously monitored and corrected based on detected deviations caused by operation amplifier offset voltage and integration capacitor leakage current. The feedback loop adjusts the sensing parameters in real-time to compensate for these errors, maintaining high sensing accuracy. This feedback-based correction ensures that even though the circuit has inherent imperfections, the final measurement remains precise.
3Ease of manufacture
If external sensing circuits are used for large-sized OLED display, then the display can be manufactured, but the display performance is suboptimal due to sensing limitations
Solution Approach 1:
The patent merges the sensing circuit functionality directly into the pixel circuit structure, creating an integrated solution that combines the advantages of both manufacturing simplicity and sensing accuracy. The sensing transistor, sensing capacitor, and sensing line are integrated with the pixel circuit components, allowing the display to be manufactured using the same process while achieving optimal display performance through accurate threshold voltage and mobility sensing. This merging eliminates the need for separate external sensing circuits that would compromise display performance.
Data Source
AI summary
A sensing circuit and a correction method thereof, a pixel driving module and a sensing method thereof, and a display apparatus, the sensing circuit includes: an operation amplifier (AMP), an integration capacitor (Cfb), a first switch (S1), a second switch (S2), a third switch (S3), a fourth switch (S4), a fifth switch (S5) and a sixth switch (S6).