Display Device Driving Transistor Compensation
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Solution Overview
Problem
Existing display devices struggle to compensate for the threshold voltage and mobility of driving transistors, leading to variations in pixel performance due to process variations.
Innovation Solution
A display device and method that include a sensing driver to generate sensing data by receiving the driving current of pixels through initialization transistors, and a driving controller to accumulate image data and compensate for input image data based on sensing data, thereby compensating for threshold voltage and mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an internal compensation circuit is used to compensate for threshold voltage, then threshold voltage compensation is achieved, but mobility compensation is not possible because the driving current cannot be sensed
Solution Approach 1:
The initialization transistor is made to serve dual purposes: its primary function of initializing the output electrode voltage, and a secondary function of enabling driving current sensing during a dedicated sensing period. This multi-functionality resolves the contradiction by allowing the same hardware component to support both threshold voltage compensation and mobility compensation without adding separate sensing circuits.
Solution Approach 2:
The patent introduces a periodic sensing operation where the initialization transistor periodically channels the driving current to the sensing driver during specific sensing periods. This periodic action allows mobility compensation to occur at designated times without interfering with the normal display operation, enabling current sensing capability that was previously lost.
2Reliability
If the initialization transistor is used for its primary function only, then initialization operation is reliable, but mobility compensation cannot be performed
Solution Approach 1:
The initialization transistor is designed to perform both initialization and current sensing functions. During normal operation, it reliably initializes the output electrode. During sensing periods, it additionally channels the driving current to the sensing driver, enabling mobility compensation. This multi-functionality maintains reliability while adding adaptability.
Solution Approach 2:
The patent makes the initialization transistor's function dynamic by controlling its on/off state through different gate signals during different periods. During sensing periods, it is activated to channel current; during normal operation, it performs initialization. This dynamic operation allows the transistor to adapt between different functions based on operational requirements.
3Manufacturing precision
If driving current is sensed through initialization transistor, then mobility compensation becomes possible, but additional sensing periods and control complexity are required
Solution Approach 1:
By making the initialization transistor multi-functional, the patent avoids adding separate dedicated sensing transistors or circuits. The same transistor handles both initialization and current sensing, reducing the need for additional components and simplifying the overall device structure despite the added sensing capability.
Solution Approach 2:
The patent merges the sensing function with the existing initialization transistor and combines the sensing operation with the existing pixel circuit structure. The sensing driver is integrated with the pixel circuit, and the sensing period is merged into the overall display refresh cycle, reducing the need for separate control mechanisms.
Data Source
AI summary
A display device includes a display panel including, a driving transistor configured to generate driving current, a light emitting element configured to emit light based on the driving current and an initialization transistor configured to apply an initialization voltage to an output electrode of the driving transistor, a sensing driver configured to generate sensing data by receiving the driving current of the pixels through initialization transistors and a driving controller configured to generate accumulated image data by accumulating input image data for frames and to compensate for the input image data based on the accumulated image data and the sensing data.