OLED Pixel Sensing Circuit for Leakage-Free Characterization
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Solution Overview
Problem
In light emitting display apparatuses, the sensing of individual light emitting devices is hindered by current leakage from adjacent devices connected to the same sensing line, leading to inaccurate sensing of device characteristics.
Innovation Solution
The apparatus includes a switching driver that selectively connects the sensing line to a data driver, allowing for separate sensing of each light emitting device by using switching control signals to isolate and measure the characteristic changes of each device independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple pixels are connected to a single sensing line for sensing light emitting device characteristics, then the sensing structure is simplified and manufacturing cost is reduced, but current leakage from adjacent pixels causes inaccurate sensing results
Solution Approach 1:
The patent divides the sensing operation into discrete time segments, where each pixel is sensed individually by controlling its corresponding switching transistor to connect to the sensing line only during its designated time slot. This temporal segmentation isolates the sensing current of each pixel, preventing current leakage from adjacent pixels from interfering with the measurement, thereby resolving the contradiction between simplified structure and accurate measurement.
2Reliability
If current sensing is performed on light emitting devices during continuous operation, then device degradation can be monitored in real-time, but current leakage from non-selected pixels interferes with accurate measurement
Solution Approach 1:
The patent applies preliminary action by pre-configuring switching control signals that selectively activate only the switching transistor corresponding to the target pixel before sensing begins. This ensures that during the sensing operation, only the selected pixel is electrically connected to the sensing line, while all other pixels remain isolated. This preliminary isolation prevents current leakage from interfering pixels, enabling accurate real-time monitoring of device characteristics without measurement interference.
3Duration of action of stationary object
If all pixels remain connected to the sensing line during sensing operations, then continuous monitoring is enabled, but current from multiple pixels combines causing inaccurate individual device sensing
Solution Approach 1:
The patent implements dynamic control by making the connection between pixels and the sensing line time-variant through switching transistors. Instead of a static permanent connection, the electrical connection is dynamically established and disconnected based on timing signals. Each pixel is connected to the sensing line only during its specific sensing time window, allowing continuous monitoring of all pixels over time while ensuring accurate individual measurement during each time slot through dynamic isolation.
Data Source
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AI summary
The light emitting display panel includes a plurality of pixels, a plurality of gate lines transferring gate signals to the plurality of pixels, a plurality of data lines transferring data voltages to the plurality of pixels, and a sensing line connected to a plurality of light emitting devices respectively included in the plurality of pixels. Each of the plurality of pixels includes a light emitting device, a sensing control transistor including a first terminal connected to a first terminal of the light emitting device and a gate connected to a sensing control line, and a sensing switching transistor including a first terminal connected to a second terminal of the sensing control transistor, a second terminal connected to the sensing line, and a gate connected to a sensing switching line.