LTPS Pixel Driving Circuit Threshold Voltage Compensation
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Solution Overview
Problem
The inconsistency in threshold voltage of driving transistors fabricated using low-temperature poly-silicon technology leads to unstable driving currents in organic light-emitting display panels, resulting in uneven brightness and display quality.
Innovation Solution
An organic light-emitting pixel driving circuit is introduced, comprising a light-emitting element, a driving transistor, initialization modules, a threshold detection module, a data write-in module, and a storage module, which initializes and detects the threshold voltage of the driving transistor, allowing for stable current generation and even display brightness through threshold voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-temperature poly-silicon (LTPS) technology is used to fabricate driving transistors, then the display panel can be manufactured with lower cost and simpler process, but the threshold voltage |Vth| has very poor evenness and may drift, leading to inconsistent driving currents
Solution Approach 1:
The patent applies preliminary action by detecting the threshold voltage of the driving transistor before the light-emitting element is driven, and pre-compensating for the threshold voltage drift through a dedicated detection module and control circuit. This preliminary detection and compensation mechanism ensures that even though LTPS transistors have inherently poor threshold voltage evenness, the actual driving current can be adjusted to achieve consistent display brightness across all pixels.
2Ease of operation
If the same grey-scale voltage is inputted to driving transistors with poor threshold voltage evenness, then the input signal is simple and easy to control, but different driving currents are generated, causing unstable working status of the organic light-emitting element
Solution Approach 1:
The patent implements feedback by using a detection module to monitor the actual threshold voltage of each driving transistor, and then using this detected information to adjust the driving current through control circuits. This feedback mechanism ensures that even though the input grey-scale voltage is the same for all pixels, the actual driving current can be dynamically adjusted based on the detected threshold voltage of each individual transistor, thereby achieving consistent light output and stable working status.
3Manufacturing precision
If threshold voltage compensation is implemented to improve display brightness evenness, then the driving current consistency is improved, but the circuit structure becomes more complex with additional modules
Solution Approach 1:
The patent applies merging by integrating the threshold voltage detection module and compensation control circuits into the existing pixel driving circuit structure. The detection module is combined with the driving transistor and light-emitting element in a unified circuit architecture, and the compensation functions are merged into the existing control signal lines and timing sequences. This integration approach minimizes the additional complexity while achieving threshold voltage compensation and improved display brightness evenness.
Data Source
AI summary
An organic light-emitting pixel driving circuit, a driving method thereof, and an organic light-emitting display panel are provided. The organic light-emitting pixel driving circuit includes a light-emitting element, a driving transistor, a first and a second initialization modules, a threshold detection module, a data write-in module, and a storage module. The driving transistor is configured to drive the light-emitting element. The first initialization module is configured to transmit a signal carried by a reference voltage line to the driving transistor. The second initialization module is configured to transmit a signal carried by an initialization signal line to the light-emitting element. The threshold detection module is configured to detect a threshold voltage of the driving transistor. The data write-in module is configured to transmit a signal carried by a data line to the pixel driving circuit. The storage module is configured to store a signal written in by the data line.