OLED Display Current Measurement Circuit with Threshold Voltage Compensation
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Solution Overview
Problem
OLED display devices experience image quality degradation due to limitations in measuring driving current and compensating threshold voltage, leading to distorted current-voltage characteristics and reduced mobility.
Innovation Solution
An OLED display device with a current measurement circuit and threshold voltage compensation circuit, including an amplifier, switches, capacitors, and an analog-to-digital converter, which initializes and measures the driving current by compensating the reference voltage with the stored threshold voltage of the OLED, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional current measurement method is used without threshold voltage compensation, then the measurement circuit is simple, but the current measurement precision deteriorates due to threshold voltage variations
Solution Approach 1:
The patent applies preliminary action by measuring and storing the threshold voltage of the OLED in advance before performing the main current measurement. The threshold voltage compensation circuit captures the threshold voltage at an initial state and uses this stored value to compensate for threshold voltage variations during subsequent driving current measurements, thereby improving measurement precision without requiring complex real-time compensation mechanisms
Solution Approach 2:
The patent introduces an intermediary element - a dedicated threshold voltage compensation circuit - that acts as a mediator between the OLED and the current measurement process. This compensation circuit specifically addresses the threshold voltage variation issue by providing corrected voltage signals to the measurement circuit, enabling accurate current measurement while maintaining overall circuit modularity
2Reliability
If threshold voltage compensation is implemented, then image quality improves, but the device complexity increases due to additional circuits
Solution Approach 1:
The patent measures and stores the threshold voltage in advance using the threshold voltage compensation circuit before the OLED undergoes significant degradation. This preliminary measurement allows the system to compensate for threshold voltage variations throughout the OLED's operational life, maintaining image quality without requiring continuous complex adjustments or frequent recalibrations
Solution Approach 2:
The patent implements feedback by using the stored threshold voltage information to continuously compensate for OLED degradation effects. The system monitors and stores threshold voltage changes over time, then uses this feedback information to adjust driving conditions and maintain consistent image quality, creating a closed-loop compensation mechanism
3Productivity
If the OLED is driven for extended periods to improve productivity, then output increases, but image quality degradation accelerates due to uncorrected threshold voltage shifts
Solution Approach 1:
The patent performs preliminary measurement and storage of the OLED's threshold voltage characteristics before extended driving periods. By capturing the initial threshold voltage state and using it for compensation during prolonged operation, the system maintains image quality consistency even during extended productivity-critical display periods, preventing acceleration of degradation effects
Solution Approach 2:
The patent establishes a feedback mechanism that continuously monitors and compensates for threshold voltage shifts during extended driving periods. The stored threshold voltage information serves as a reference for real-time compensation, allowing the system to maintain image quality and reliability even during prolonged high-productivity operation
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
The solution effectively compensates for OLED deterioration, enhancing image quality by maintaining consistent current direction regardless of reference voltage magnitude, thus improving the display's performance and longevity.
Implementation Method 1
OLED display devices, which generate light by recombination of electrons and holes
Data Source
AI summary
An organic light emitting diode display device including a display panel including a pixel, a power supply configured to apply a voltage to the pixel, and a current measurement circuit connected to the pixel, wherein the pixel includes a pixel circuit and an organic light emitting diode, the pixel circuit including a plurality of switching elements and one or more capacitors, and wherein the current measurement circuit includes a current integration circuit including an amplifier, the amplifier including a first input terminal, a second input terminal, and an output terminal, the first input terminal being connected to the pixel circuit, a threshold voltage compensation circuit connected to the second input terminal of the amplifier, and an analog-to-digital converter connected to the output terminal of the amplifier.