OLED Pixel Circuit Dynamic Reference Voltage Compensation
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Solution Overview
Problem
Existing OLED display devices face issues with brightness uniformity and consistency due to varying threshold voltages of driving transistors, leading to limited compensation ranges in compensation circuits, which can invalidate some circuits and affect display quality.
Innovation Solution
An OLED pixel circuit with a reference signal generation module that adjusts the reference signal based on the current threshold voltage of the driving transistor, ensuring the voltage meets validation conditions to validate the compensation circuit, thereby enlarging the compensation range and maintaining brightness consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference voltage is provided to all OLED pixels, then the circuit structure is simple, but the compensation range is limited and brightness uniformity deteriorates when threshold voltage shifts exceed the compensation range
Solution Approach 1:
The patent implements dynamic reference voltage adjustment by introducing a reference voltage adjustment circuit that modifies the reference voltage based on the actual threshold voltage of the driving transistor. This transforms the static reference voltage system into a dynamic one, enabling the compensation circuit to adapt to different threshold voltage conditions and expand the compensation range while maintaining circuit simplicity.
Solution Approach 2:
The patent changes the reference voltage parameter dynamically to match the threshold voltage variations of the driving transistor. By adjusting the reference voltage parameter based on actual transistor characteristics, the system maintains effective compensation across a wider range of threshold voltage shifts without significantly increasing circuit complexity.
2Ease of manufacture
If identical compensation circuits are provided for all OLED pixels, then the manufacturing process is simplified, but some compensation circuits become invalidated when threshold voltage variations exceed the fixed compensation range
Solution Approach 1:
The patent applies local quality by making each compensation circuit's reference voltage adjustable according to the specific characteristics of its corresponding driving transistor. This allows each pixel circuit to be optimized locally for its specific threshold voltage, ensuring compensation circuit validity across all pixels while maintaining a standardized overall circuit architecture that simplifies manufacturing.
Solution Approach 2:
The patent performs preliminary characterization of the driving transistor's threshold voltage during manufacturing or initialization, and uses this information to pre-adjust the reference voltage for each compensation circuit. This preliminary action ensures that each compensation circuit is properly configured before operation, preventing invalidation due to threshold voltage variations.
3Reliability
If the reference voltage is adjusted based on current threshold voltage, then the compensation range is enlarged and brightness uniformity is maintained, but the circuit complexity increases due to the reference signal generation module
Solution Approach 1:
The patent introduces an intermediary reference voltage adjustment circuit that acts as a mediator between the fixed reference voltage source and the compensation circuit. This intermediary component translates the fixed reference voltage into an adjusted reference voltage based on the driving transistor's threshold voltage, enabling dynamic compensation while keeping the overall circuit structure relatively simple through functional decomposition.
Data Source
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AI summary
The present disclosure provides an OLED pixel circuit, a display device and a control method. The OLED pixel circuit includes: an OLED; a driving transistor; a first switching unit configured to connect a data signal output end and a gate electrode of the driving transistor; a second switching unit configured to connect a power signal output end and a source electrode of the driving transistor; a compensation circuit connected to the gate electrode of the driving transistor and configured to maintain a voltage of the gate electrode of the driving transistor during a light-emitting period, so as to enable a current flowing through the OLED to be irrelevant to a threshold voltage Vth of the driving transistor; and a reference signal generation module configured to generate, based on a current threshold voltage of the driving transistor, a reference signal to be used by the compensation circuit, wherein a voltage of the reference signal and the threshold voltage meet at least one of validation conditions capable of validating the compensation circuit.