Pixel Drive Circuit Threshold Voltage Compensation
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Solution Overview
Problem
In display apparatuses, the drift in threshold voltages of transistors used to drive light-emitting diodes leads to uneven brightness due to the integration of high-density micro light-emitting diodes, causing issues with brightness uniformity.
Innovation Solution
A pixel drive circuit is designed with a data write sub-circuit, input and read sub-circuit, drive sub-circuit, and output control sub-circuit, which includes transistors and storage capacitors to manage data transmission, threshold voltage read, and drive signal output, ensuring that the drive current is independent of the threshold voltage drift, thereby maintaining consistent brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If high-density micro light-emitting diodes are integrated on one chip, then the display apparatus achieves thinning, miniaturization and matrixing, but threshold voltages of transistors drift causing uneven brightness
Solution Approach 1:
The patent applies preliminary action by reading the threshold voltage of the drive transistor before the display period and storing it in a storage capacitor. This advance measurement and storage of threshold voltage enables subsequent compensation during the display period, preventing brightness uniformity issues caused by threshold voltage drift while maintaining high-density micro LED integration
Solution Approach 2:
The patent implements feedback by using the read threshold voltage to generate a compensated data signal that accounts for transistor threshold variations. The system continuously monitors threshold voltage through the input and read sub-circuit and adjusts the drive signal accordingly, creating a closed-loop control that maintains brightness uniformity despite threshold drift in high-density configurations
2Illumination intensity
If threshold voltage compensation is implemented, then brightness uniformity is improved, but device complexity increases due to additional sub-circuits
Solution Approach 1:
The patent merges multiple functions into integrated sub-circuits: the input and read sub-circuit handles both signal input and threshold voltage reading, while the drive sub-circuit integrates data writing and compensation operations. This consolidation achieves threshold voltage compensation and brightness uniformity improvement without proportionally increasing device complexity through separate dedicated components for each function
Data Source
AI summary
A pixel drive circuit includes a data write sub-circuit, an input and read sub-circuit, a drive sub-circuit, and a first output control sub-circuit. The data write sub-circuit is configured to transmit data signals input from a first data voltage terminal at different times to a first node. The input and read sub-circuit is configured to: transmit a signal of a signal transmission terminal to a second node in a write period, and transmit an electrical signal of the second node to the signal transmission terminal in a threshold voltage read period. The drive sub-circuit is configured to output a drive signal. The first output control sub-circuit is configured to: be coupled to an element to be driven, and transmit the drive signal output by the drive sub-circuit to the element to be driven.