Display Device Pixel Circuit Compensation Power Supply Line
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Solution Overview
Problem
Active matrix displays face challenges in manufacturing driving transistors with equal threshold voltages due to manufacturing process variables, leading to threshold voltage differences among pixels, which affects display uniformity and efficiency, especially in high-resolution organic light-emitting displays.
Innovation Solution
The display device incorporates a compensation power supply line and additional transistors in the pixel circuit to stabilize the voltage across storage capacitors, allowing for simultaneous data writing and threshold voltage compensation during two horizontal periods, enhancing the charging rate and reducing IR drops in the power supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional pixel circuit is used, then the device complexity is low, but the threshold voltage difference among pixels causes display non-uniformity
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation during the data writing period (first horizontal period) before the pixel needs to maintain stable voltage during the emission period. The compensation circuit adjusts the storage capacitor voltage in advance to counteract expected threshold voltage variations, allowing the pixel to operate uniformly without complex continuous compensation mechanisms.
Solution Approach 2:
The patent implements feedback through the compensation circuit that monitors and adjusts the storage capacitor voltage based on the actual threshold voltage deviations. The compensation circuit receives feedback about voltage differences and automatically adjusts the compensation voltage to maintain uniform pixel operation, resolving the contradiction between simplicity and precision.
2Productivity
If data writing and threshold voltage compensation are performed simultaneously, then the charging rate improves, but the device complexity increases
Solution Approach 1:
The patent merges the data writing operation and threshold voltage compensation operation into a single time period (first horizontal period). By combining these two functions that were previously performed separately, the patent achieves faster charging rates and improved productivity without requiring additional time or complex separate compensation circuits, thus resolving the contradiction between productivity and device complexity.
3Manufacturing precision
If the storage capacitor voltage is stabilized, then the display uniformity improves, but the loss of energy increases due to additional compensation
Solution Approach 1:
The patent applies periodic action by performing threshold voltage compensation only during the first horizontal period when data writing occurs, rather than continuously compensating throughout the entire frame period. The compensation circuit is activated periodically during data writing and remains inactive during the emission period, achieving voltage stability while minimizing energy loss from continuous compensation operations.
Data Source
AI summary
A display device includes a plurality of pixels and a compensation power supply line. The pixels are located at intersections of data lines and gate lines. The compensation power supply line is separated from the data lines. Each of the pixels includes an in-pixel circuit and at least one out-pixel circuit. The in-pixel circuit includes a first transistor, to be controlled based on a data voltage from a corresponding one of the data lines, and a storage capacitor connecting the first transistor and a first node. The at least one out-pixel circuit receives a compensation voltage from the compensation power supply line and provides the compensation voltage to the first node.