Display Driving Circuit Threshold Voltage Compensation
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Solution Overview
Problem
In high-resolution display devices, the difference in threshold voltages of transistors across pixels leads to significant deviations in driving current, causing luminance variations and an hourglass phenomenon, which is exacerbated by the need for numerous transistors and signal lines in the row direction, making it difficult to meet market demands for high-resolution displays.
Innovation Solution
A display driving circuit with a pixel unit comprising mirrored transistors and a current control module that stabilizes the threshold voltage, reducing the number of transistors and signal lines required by using a mirror-constant-current-source structure to accurately control the driving current, thereby simplifying the circuit structure and reducing the pixel unit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threshold voltage compensation circuit is implemented by adding transistors and signal lines in row direction, then threshold voltage compensation is achieved, but the number of transistors and signal lines increases making it impossible to meet high-resolution requirements
Solution Approach 1:
The patent merges the threshold voltage compensation function with the existing pixel circuit structure by utilizing the light-emitting element's inherent characteristics. The compensation is achieved through the interaction between the light-emitting element and the transistor without requiring separate dedicated compensation transistors or signal lines, thus integrating multiple functions into a unified circuit architecture.
Solution Approach 2:
The light-emitting element itself serves the dual purpose of both light emission and threshold voltage compensation. By leveraging the light-emitting element's electrical characteristics during its operation, the circuit automatically compensates for threshold voltage variations without requiring external compensation mechanisms, making the system self-sufficient.
2Measurement precision
If more transistors are added for threshold voltage compensation, then compensation accuracy improves, but pixel area increases reducing display resolution
Solution Approach 1:
The existing transistor in the pixel circuit is made multi-functional, serving both as the driving transistor for light emission and as the compensation transistor for threshold voltage correction. This universal approach allows the same component to perform multiple critical functions, eliminating the need for additional dedicated compensation transistors and reducing pixel area.
Solution Approach 2:
The patent utilizes changes in electrical parameters (voltage and current) during the light-emitting element's operation to achieve threshold voltage compensation. By monitoring and utilizing parameter variations inherent to the light-emitting element's characteristics, the system achieves accurate compensation without requiring additional hardware components.
3Reliability
If threshold voltage differences between transistors exceed 0.1V, then driving current deviation occurs causing luminance variation, but increasing transistors for compensation increases circuit complexity
Solution Approach 1:
The circuit implements a feedback mechanism where the light-emitting element's electrical characteristics are continuously monitored during operation. The observed current-voltage relationships provide feedback information about threshold voltage variations, which is then used to adjust the driving signal accordingly, maintaining luminance uniformity across different pixels.
Solution Approach 2:
The patent creates a composite circuit structure that combines the light-emitting element with the driving transistor in a unified configuration. This composite approach allows the system to leverage the unique properties of each component (the light-emitting element's nonlinear characteristics and the transistor's amplification capability) to achieve threshold voltage compensation and luminance uniformity.
Data Source
AI summary
The application provides a display driving circuit, an array substrate, a circuit driving method, and a display device. The array substrate comprises a plurality of rows of scan lines, a plurality of columns of data lines, and a plurality of pixel units being defined by intersecting of the plurality of rows of scan lines and the plurality of columns of data lines; each column of data lines being connected to a reset module; each column of data lines being further connected to a current control module configured to form a first current flowing from a data line connected thereto to a reference voltage line, wherein the pixel unit includes a first transistor and a second transistor, the first transistor and the second transistor have device parameters that are the same or in a predetermined proportion, and a second electrode of the second transistor is connected to the output terminal.