Display Pixel Compensation Circuit for Transistor Mobility Variation
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Solution Overview
Problem
Existing display devices suffer from mobility variation in driving transistors due to temperature fluctuations, leading to variations in luminance and reliability issues.
Innovation Solution
A display device with a compensation capacitor and a capacitor system that stores sampled values of the driving transistor's mobility and threshold voltage, using a capacitance ratio of 1:0.05 to 1:0.3, to compensate for mobility variations and stabilize the driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sampling capacitor is used to store sampled values of the driving transistor, then the device complexity is reduced, but the manufacturing precision of luminance compensation deteriorates
Solution Approach 1:
The sampling capacitor is divided into two separate capacitors: a first sampling capacitor that stores a first sampled value (related to threshold voltage) and a second sampling capacitor that stores a second sampled value (related to mobility). This segmentation allows each capacitor to be optimized for its specific sampling function, improving the overall precision of mobility variation compensation while maintaining manageable device complexity through modular design.
2Ease of manufacture
If the capacitance ratio of the first sampling capacitor to the second sampling capacitor is not optimized, then the ease of manufacture is improved, but the reliability of mobility compensation deteriorates
Solution Approach 1:
The patent specifies an optimized capacitance ratio range (1:0.05 to 1:0.3) between the first sampling capacitor and the second sampling capacitor. This parameter optimization ensures that the first sampled value (threshold voltage) and the second sampled value (mobility) are weighted appropriately during compensation, achieving reliable mobility variation compensation. The ratio balances manufacturing feasibility with compensation effectiveness.
3Device complexity
If no compensation for mobility variation is implemented, then the device complexity is reduced, but the display quality and operation reliability deteriorate due to temperature-induced mobility variation
Solution Approach 1:
The patent implements a feedback mechanism where the driving transistor's parameters (threshold voltage and mobility) are sampled during non-display periods, stored in separate sampling capacitors, and then used to compensate for mobility variations during display operation. This feedback loop continuously adjusts for temperature-induced mobility changes, maintaining stable luminance and improving operation reliability without excessive complexity.
Solution Approach 2:
The patent performs preliminary sampling of the driving transistor's threshold voltage and mobility parameters during non-display periods before actual display operation begins. By pre-sampling and storing these values in the first and second sampling capacitors, the system prepares compensation data in advance, enabling real-time correction of mobility variations during display without interrupting the imaging process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves display quality and enhances operation reliability by reducing the influence of mobility variation in driving transistors due to temperature changes and luminance variations.
Implementation Method 1
a compensation capacitor configured to store a first sampled value of the driving transistor for a first period of time based on a high-level voltage and a reference voltage
Implementation Method 2
a capacitor configured to store a second sampled value of the driving transistor for a second period of time based on the high-level voltage and the reference voltage
Data Source
AI summary
Disclosed is a display device including a display panel including subpixels, and a driver configured to drive the display panel, wherein each of the subpixels includes a light-emitting diode, a driving transistor configured to generate a driving current, a compensation capacitor configured to store a first sampled value of the driving transistor for a first period of time based on a high-level voltage and a reference voltage, a capacitor configured to store a second sampled value of the driving transistor for a second period of time based on the high-level voltage and the reference voltage, and a compensation transistor configured to sum the first sampled value stored in the compensation capacitor and the second sampled value stored in the capacitor.