OLED Pixel Circuit Stabilizes Current via Threshold Compensation
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Solution Overview
Problem
Current OLED display technologies face issues with non-uniform brightness due to varying threshold voltages of driver transistors and IR Drop, leading to inconsistent current flow and image quality.
Innovation Solution
An OLED pixel circuit with a specific configuration of subcircuits and transistors that maintains a stable working current independent of threshold voltage and power supply voltage, using a diode or source-follow connection to control the driver transistor, and a storage subcircuit to maintain a stable voltage difference, ensuring the current is related only to the data and initial signal voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OLED pixel circuits are used, then the circuit can drive the OLED to emit light, but the working current varies due to threshold voltage changes and IR Drop, causing non-uniform brightness
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the light emission phase. During the compensation phase, the circuit measures and stores the threshold voltage value in a storage unit, so that when light emission occurs, the driving current has already been adjusted to account for threshold voltage variations, ensuring uniform brightness across different pixels
Solution Approach 2:
The patent implements feedback by using the measured threshold voltage to adjust the driving current. The storage unit holds the threshold voltage information, and this information feeds back to the driving unit to modify the working current, creating a closed-loop system that compensates for parameter variations and maintains current stability
2Ease of manufacture
If simple pixel circuit structures are used, then manufacturing is easier, but threshold voltage variations and IR Drop cause non-uniform current distribution
Solution Approach 1:
The patent segments the pixel circuit into distinct functional modules: a driving unit for current control, a storage unit for threshold voltage retention, and a compensation unit for adjustment. This segmentation allows each module to perform its specific function independently, making the circuit easier to manufacture while achieving reliable current consistency through coordinated operation of the segments
Solution Approach 2:
The patent introduces a storage unit as an intermediary between the threshold voltage measurement and the driving current generation. This intermediary component stores the threshold voltage information and enables its use in current regulation without requiring complex real-time calculation circuits, thus maintaining ease of manufacture while improving current consistency
3Manufacturing precision
If compensation circuits are added to eliminate threshold voltage influence, then current stability improves, but circuit complexity increases
Solution Approach 1:
The patent applies local quality by implementing compensation only where needed - specifically in the pixel-level driving circuit where threshold voltage variations affect current. The compensation mechanism is localized to the individual pixel circuit rather than requiring global circuit modifications, thus improving current stability without excessively increasing overall device complexity
Solution Approach 2:
The patent changes the operating parameters of the driving transistor by adjusting the gate voltage based on stored threshold voltage information. This parameter change approach allows the circuit to maintain stable current despite variations in transistor characteristics, achieving current stability through parameter adjustment rather than complex circuit topology
4Reliability
If power supply voltage is increased to compensate for IR Drop, then current uniformity improves, but power consumption increases
Solution Approach 1:
The patent applies preliminary action by measuring and storing the actual voltage at the power supply node before light emission. This pre-measurement allows the circuit to compensate for IR Drop effects by adjusting the driving current based on the actual voltage level, eliminating the need to increase power supply voltage and thus avoiding increased power consumption
Data Source
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AI summary
An electronic circuit for driving an electronic component is disclosed. The electronic circuit includes a drive subcircuit, a first subcircuit, a second subcircuit, a third subcircuit, a fourth subcircuit, and a fifth subcircuit. Under control of a data signal terminal, a scan signal terminal, a first control signal terminal, a second control signal terminal, a first power supply terminal, and a second power supply terminal, the drive subcircuit is configured to have a diode connection or a source-follow connection so as to maintain a substantially stable working current running through the electronic component. The electronic circuit can be a pixel circuit, and the electronic component can be a light-emitting component comprising an organic light-emitting diode (OLED). A display panel and a display apparatus containing the electronic circuit, as well as a method for driving the electronic circuit are also disclosed.