Display Panel Sampling Circuit for Threshold-Voltage Sampling
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Solution Overview
Problem
As resolution increases in display devices, the reduced horizontal period for one frame leads to insufficient sampling time for the threshold voltage of the driving transistor, resulting in luminance non-uniformity and pixel defects.
Innovation Solution
A sampling transistor and a sampling capacitor are added between the light-emitting element and the driving element to secure a sufficient sampling time for the threshold voltage, with additional scan signals applied to ensure proper compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resolution is increased to improve display quality, then image quality is improved, but horizontal period is reduced causing insufficient sampling time for threshold voltage
Solution Approach 1:
The patent applies preliminary action by adding a sampling transistor that performs threshold voltage sampling before the main driving operation. This preliminary sampling action ensures that the threshold voltage is accurately captured in advance, allowing the system to maintain sufficient sampling time even when the overall horizontal period is reduced due to higher resolution requirements.
2Productivity
If horizontal period is reduced to increase refresh rate, then productivity is improved, but sampling time for threshold voltage becomes insufficient
Solution Approach 1:
The patent applies segmentation by dividing the timing period into separate functional segments: a dedicated sampling phase for threshold voltage measurement and a separate driving phase. This segmentation allows the sampling operation to be isolated and optimized, ensuring sufficient sampling time even when the total horizontal period is reduced to achieve higher refresh rates.
3Productivity
If sampling time is insufficient, then productivity is maintained, but luminance non-uniformity occurs reducing display quality
Solution Approach 1:
The patent applies feedback by using the sampled threshold voltage information to adjust and compensate for luminance variations. The sampling transistor captures the actual threshold voltage, and this feedback information is used to correct luminance non-uniformity, ensuring uniform display quality while maintaining high frame rates.
Data Source
AI summary
Disclosed is a display panel in which a sampling transistor and a sampling capacitor for additional sampling are disposed between a light-emitting element and a driving element of the display panel to secure a sufficient sampling time of the driving element. Further, a display device including the panel is disclosed. To this end, a first switching element is configured to be switched to apply an initialization voltage to each of a first electrode of the light-emitting element and a gate electrode of the driving element; and a second switching element is configured to be switched to apply a sampling voltage to a second electrode and the gate electrode of the driving element. Thus, a sufficient sampling time of a threshold voltage of the driving element is secured such that pixel defects such as luminance non-uniformity of pixels are reduced.