Semiconductor Device Threshold Voltage Compensation Circuit
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Solution Overview
Problem
Current semiconductor devices, particularly those using current-driving-type light-emitting elements like OLEDs, face issues with variations in transistor threshold voltage, mobility, and current characteristics, leading to display unevenness and reduced image quality.
Innovation Solution
A semiconductor device structure incorporating a transistor, load, and capacitors, with specific switch configurations and voltage management to correct variations in threshold voltage and mobility, allowing for efficient current supply to a load, thereby reducing adverse effects on display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transistor designs are used in current-driving light-emitting elements, then device simplicity is maintained, but variations in threshold voltage and mobility cause display unevenness and reduced image quality
Solution Approach 1:
The patent measures and stores threshold voltage and mobility parameters of transistors before they are used in the pixel circuit. By performing these measurements in advance and storing the data in capacitors, the circuit can compensate for transistor variations without adding complex real-time correction mechanisms, thus improving manufacturing precision while controlling device complexity
Solution Approach 2:
The patent introduces intermediate measurement circuits and storage capacitors that act as mediators between the transistor parameters and the pixel circuit operation. These intermediaries capture and store threshold voltage and mobility data, allowing the pixel circuit to use corrected current values that account for transistor variations, thereby improving display uniformity without significantly increasing overall device complexity
2Manufacturing precision
If more transistors are added to correct transistor variations, then display uniformity improves, but the number of transistors and wirings increases
Solution Approach 1:
The patent designs measurement circuits and storage capacitors that serve multiple functions: they measure transistor parameters, store the measured values, and provide correction data for current driving. This multi-functionality allows the same circuit elements to address multiple issues (threshold voltage variation and mobility variation) without proportionally increasing the number of transistors and wirings, thus improving display uniformity while controlling component quantity
Solution Approach 2:
The patent combines the measurement, storage, and correction functions into an integrated circuit architecture where measurement circuits and storage capacitors work together as a unified system. By merging these functions rather than implementing them as separate independent components, the patent reduces the total number of transistors and wirings needed while achieving improved display uniformity through comprehensive transistor parameter compensation
Data Source
AI summary
By holding a voltage that depends on a video signal in a first capacitor, holding a voltage that depends on a threshold voltage of a transistor in a second capacitor, and then applying a total voltage of the voltage held in the first capacitor and the voltage held in the second capacitor between a source and a gate of the transistor, even when the threshold voltage varies, a current corresponding to the video signal can be supplied to a load. The voltage that depends on the video signal and the voltage that depends on the threshold voltage of the transistor are separately acquired.