OLED Driving Transistor Threshold and Mobility Sensing
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Solution Overview
Problem
Existing OLED display devices face challenges in accurately detecting and compensating for threshold voltage and mobility characteristics of driving transistors, leading to non-uniform luminance due to manufacturing process deviations, which current sensing methods are inefficient and require additional memory.
Innovation Solution
An OLED display device structure that includes a data driver with first and second current sources and an ADC to detect threshold voltage and mobility characteristics by applying different currents and sensing voltages, allowing for simultaneous detection of these parameters within a short time frame, reducing the sensing period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate sensing methods are used for threshold voltage and mobility characteristics, then detection accuracy is improved, but sensing time increases and additional memory is required
Solution Approach 1:
The patent combines separate sensing methods for threshold voltage and mobility characteristics into a unified dual-mode sensing architecture. The sensing unit integrates both slow-mode sensing (for threshold voltage) and fast-mode sensing (for mobility) operations, allowing simultaneous or sequential execution without requiring additional memory storage. This merging eliminates the need for separate memory resources while reducing total sensing time through optimized operation sequencing.
Solution Approach 2:
The sensing unit is designed with multi-functionality to perform both threshold voltage sensing and mobility characteristic sensing using the same hardware resources. By making the sensing unit universal, the patent eliminates redundant components and memory requirements, achieving both detection accuracies through a single integrated structure that can operate in different modes as needed.
2Manufacturing precision
If external compensation method is used, then luminance non-uniformity is reduced, but device complexity increases due to additional current source positioning
Solution Approach 1:
The patent extracts the compensation function from external current sources and relocates it directly into the pixel structure. By integrating the compensation capability within each pixel's driving transistor and sensing unit, the design eliminates the need for external current source positioning while maintaining luminance uniformity compensation. This extraction reduces device complexity by removing external components and simplifying the overall architecture.
3Measurement precision
If pixel-level sensing is implemented, then compensation accuracy is improved, but sensing period increases due to individual pixel measurement requirements
Solution Approach 1:
The patent implements periodic sensing operations where the sensing unit alternates between slow-mode sensing for threshold voltage characteristics and fast-mode sensing for mobility characteristics. This periodic action allows pixel-level compensation accuracy by measuring individual pixel parameters while optimizing the timing and sequencing of measurements to improve overall sensing efficiency and reduce the total sensing period.
Data Source
AI summary
An organic light emitting diode display device includes: an organic light emitting diode; a driving transistor having a first electrode, a second electrode, and a third electrode, the first electrode coupled to the variable driving voltage source and controlling the operation of the organic light emitting diode depending on a voltage difference between the third electrode and the second electrode; a first current source for supplying a first current to the third electrode and the second electrode of the driving transistor through a data line; a second current source for supplying a second current to the third electrode and the second electrode of the driving transistor through the data line; and a digital-to-analog converter for detecting the level of a sensing current flowing between the first and second electrodes of the driving transistor through the data line.