Pixel Compensation Circuit for AMOLED Display Uniformity
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Solution Overview
Problem
AMOLED display substrates face issues with uneven display due to variations in threshold voltage and electron mobility of driving transistors, leading to differences in driving capabilities, which existing compensation methods struggle to address effectively.
Innovation Solution
A pixel compensation device and method that includes a controller and external compensation circuits connected to pixel driving circuits, utilizing input circuits and sensing circuits to transmit and sense voltages and currents, determining actual characteristic values, and correcting data voltages to ensure uniform display by compensating for threshold voltages and aging of light-emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing compensation methods are used, then some threshold voltage compensation is achieved, but the compensation accuracy is insufficient due to variations in electron mobility and threshold voltage
Solution Approach 1:
The patent implements a feedback mechanism where the sensing circuit measures the actual threshold voltage of the driving transistor and feeds this information back to the controller. The controller then adjusts the data voltage accordingly to compensate for threshold voltage variations, achieving accurate compensation and uniform display quality
Solution Approach 2:
The pixel circuit performs self-diagnosis and self-compensation by using the sensing circuit to detect its own threshold voltage and electron mobility characteristics. The measured values are used to automatically adjust the driving parameters without external intervention, improving both accuracy and reliability
2Device complexity
If no external compensation circuit is used, then the pixel circuit structure is simple, but threshold voltage variations cause uneven display
Solution Approach 1:
The patent introduces an external compensation circuit as an intermediary component that includes a sensing circuit and a controller. This intermediary measures the threshold voltage and electron mobility of the driving transistor and provides compensation signals, achieving uniform display without significantly complicating the pixel circuit structure
Solution Approach 2:
The compensation function is segmented from the pixel circuit and implemented as a separate external compensation circuit. This segmentation allows the pixel circuit to remain relatively simple while the dedicated compensation circuit handles the complex measurement and adjustment functions, improving display uniformity
3Ease of operation
If threshold voltage compensation is not performed, then the driving circuit operates simply, but differences in driving capabilities lead to display inconsistencies
Solution Approach 1:
The patent performs preliminary measurement of the threshold voltage and electron mobility characteristics before the actual display operation. The sensing circuit measures these parameters in advance, and the controller pre-calculates the compensation values, ensuring consistent display performance from the start of operation
Data Source
AI summary
A pixel compensation device includes a controller and at least one external compensation circuit. In the external compensation circuit, a first input circuit is configured to transmit a first voltage to a first terminal of a driving sub-circuit in a initialization phase, perform blanking in a pre-storage phase, and transmit a threshold compensation voltage to the first terminal in the data compensation writing phase; a second input circuit is configured to transmit a second voltage to a control terminal of the driving sub-circuit in the initialization phase and the pre-storage phase, so that a voltage of the first terminal changes from the first voltage to the threshold compensation voltage in the pre-storage phase; a sensing circuit is configured to sense the threshold compensation voltage in the data compensation writing phase; and the controller is configured to transmit a data voltage to the control terminal in the data compensation writing phase.