External Compensation Circuit for OLED Display Precision
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Solution Overview
Problem
Conventional active matrix OLEDs face challenges in maintaining brightness uniformity and display precision due to degradation of driving transistors and organic light emitting diodes over time, making it difficult to compensate for changing working parameters.
Innovation Solution
An external compensation circuit is introduced, comprising a power supply unit, sampling unit, and data signal generation unit, which samples voltage signals from driving transistors and organic light emitting diodes, compares them with pre-stored characteristic curves, and generates compensated data signals to improve threshold voltage and mobility compensation, thereby enhancing display precision and drive capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If internal compensation circuit is used in conventional active matrix OLED, then device complexity is reduced, but compensation precision deteriorates due to parameter degradation over time
Solution Approach 1:
The patent introduces an external compensation circuit as an intermediary component that connects to the pixel driving circuit through data signal lines. This external circuit performs precise measurement and compensation operations separately, then feeds back corrected data signals to the pixel driving circuit, achieving high compensation precision without increasing the complexity of the pixel-level circuit itself.
Solution Approach 2:
The compensation function is segmented into a separate external compensation circuit rather than being integrated within the pixel driving circuit. This segmentation allows the compensation circuit to have more resources for precise measurement and processing, while the pixel driving circuit remains simple and dedicated to driving the OLED.
2Productivity
If conventional active matrix driving is used, then productivity is improved through simultaneous pixel emission, but brightness uniformity deteriorates due to parameter degradation
Solution Approach 1:
The external compensation circuit continuously monitors the actual emission characteristics of the OLED and compares them with expected values. When degradation is detected, the circuit calculates compensation values and adjusts the data signals sent to the pixel driving circuit, creating a closed-loop feedback system that maintains brightness uniformity while preserving the high emission efficiency of active matrix driving.
Data Source
AI summary
The present application discloses a display panel and a display device. The display panel comprises a plurality of data signal lines; a plurality of scan signal lines intersecting with the plurality of data signal lines, to define a plurality of sub-pixels in an array, and each of the sub-pixels comprising a pixel driving circuit, and an external compensation circuit, comprising a power supply unit, a sampling unit and a data signal generation unit, being connected to the data signal lines, and transmitting a compensated data signal via the data signal lines to the pixel driving circuits. In the present implementation, voltage compensation is performed by the external compensation circuit on the driving transistor and the organic light emitting diode in the pixel driving circuit, to improve the driving capability of the pixel driving circuit and increases the display precision of the display panel.