LTPO Pixel Circuit Sensing for Uniform Transistor Aging
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Solution Overview
Problem
Existing display technologies using Low Temperature Polycrystalline Oxide (LTPO) face issues with varying aging degrees of driving transistors in pixel circuits, leading to reduced display effect, service life, and reliability due to unmonitored threshold voltages.
Innovation Solution
A display substrate design with specific transistor configurations and signal connections, including a third control sub-circuit to provide consistent voltage to pixel circuits, allowing monitoring of threshold voltages and external compensation, thereby stabilizing the aging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LTPO technology is used for display substrate, then power consumption is reduced and response speed is improved, but aging degrees of driving transistors vary leading to reduced display effect and reliability
Solution Approach 1:
The patent introduces a sensing transistor connected in parallel with the driving transistor, both sharing the same light emitting element. The sensing transistor's threshold voltage changes reflect the aging characteristics of the driving transistor. By monitoring the sensing transistor's electrical characteristics (through current measurements during display operation), the system obtains feedback information about the driving transistor's aging state, enabling threshold voltage compensation to maintain consistent display effect despite aging variations.
2Ease of manufacture
If traditional pixel circuit configuration is used, then manufacturing is simpler, but threshold voltages cannot be monitored leading to varying aging degrees
Solution Approach 1:
The patent uses the sensing transistor as an intermediary element to indirectly monitor the driving transistor's threshold voltage. Instead of directly measuring the driving transistor's characteristics (which would require complex circuit modifications), the sensing transistor serves as a proxy that replicates the aging behavior. By measuring the sensing transistor's current through the light emitting element during normal display operation, the system infers the driving transistor's threshold voltage state without disrupting the simple pixel circuit architecture.
3Device complexity
If no external compensation is implemented, then device complexity is lower, but service life is reduced due to unmonitored threshold voltages
Solution Approach 1:
The pixel circuit performs self-diagnosis and self-compensation for aging effects. The sensing transistor automatically tracks the driving transistor's threshold voltage drift over time, and the compensation circuitry (integrated within the pixel circuit) automatically adjusts the driving voltage to compensate for aging. This self-service mechanism extends the display substrate's service life by maintaining display quality without requiring external monitoring systems or complex replacement schedules.
Data Source
AI summary
A display substrate and a display apparatus are provided, the display substrate includes: a base substrate and at least one pixel circuit, at least one first power supply line and at least one electrode connection line provided on the base substrate, adjacent pixel circuits located on a same row as the pixel circuit include a first adjacent pixel circuit and a second adjacent pixel circuit; the at least one pixel circuit includes a fifth transistor, a first electrode of the fifth transistor is electrically connected to the first power supply line, the first electrode of the fifth transistor of the at least one pixel circuit and a first electrode of the fifth transistor of the first adjacent pixel circuit are respectively connected with the electrode connection line.