OLED Display Driving Sensing Power Source Line Compensation
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Solution Overview
Problem
Organic light emitting display devices face issues with deteriorated organic light emitting diodes and driving transistors, leading to suboptimal image luminance due to the lack of effective compensation methods.
Innovation Solution
The device senses current flowing in the power supply voltage line and calculates a threshold voltage for the driving transistor using a sensing mode that involves sampling currents at different data voltages, allowing for image quality compensation without adding sensing transistors or lines to the pixel circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal compensation method using compensation circuit located in pixel is used, then pixel deterioration can be compensated, but device complexity increases
Solution Approach 1:
The patent merges the sensing function into the existing power source line by sampling current from the power source line during normal operation. Instead of adding separate sensing circuits to each pixel, the invention combines the deterioration detection function with the existing power delivery infrastructure, thereby compensating for pixel deterioration without increasing device complexity
Solution Approach 2:
The power source line is given multiple functions: it serves both as the power delivery path for pixel operation and as the sensing path for current sampling. By making the power source line universal, the invention eliminates the need for dedicated sensing circuits in each pixel, thus maintaining simple circuit structure while achieving deterioration compensation
2Reliability
If external compensation method using compensation circuit located outside panel is used, then pixel deterioration can be compensated, but measurement precision decreases
Solution Approach 1:
The patent segments the measurement process by sampling current from individual power source lines that supply specific pixels. By measuring current at the pixel level through the power source line rather than averaging across the entire panel, the invention achieves precise deterioration measurement for individual pixels while using external compensation circuitry
Solution Approach 2:
The invention implements feedback by continuously sampling the current flowing through the power source line and using this information to calculate and compensate for pixel deterioration. The sensed current provides real-time feedback about pixel state, enabling dynamic adjustment of compensation parameters to maintain measurement precision
3Measurement precision
If sensing transistor and sensing line are added to pixel circuit, then current sensing accuracy improves, but device complexity increases
Solution Approach 1:
The power source line serves itself by performing both its original function of delivering power to pixels and the additional function of carrying sensing current. The existing power source line structure is utilized for sensing purposes without requiring separate dedicated sensing infrastructure, thus achieving accurate current sensing while avoiding increased pixel circuit complexity
Data Source
AI summary
An organic light emitting display device includes a display part including a plurality of scan lines, a plurality of data lines, a plurality of power source lines, and a plurality of pixels each including an organic light emitting diode, a driving transistor coupled to the organic light emitting diode and to a power source line of the power source lines, and a switching transistor coupled to a scan line of the scan lines and to a data line of the data lines, and a sensing driver configured to sample a sensing current from the power source line while a sensing data voltage is applied to one of the pixels, and to calculate a threshold voltage value of the driving transistor using the sensing current in a sensing mode.