OLED Driving Characteristic Detection Circuit for Pixel Compensation
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Solution Overview
Problem
Conventional OLED display devices face challenges in accurately detecting the electrical characteristics of driving TFTs due to deviations in threshold voltage and electron mobility, leading to luminance inconsistencies between pixels, which existing voltage sensing-based compensation methods fail to address effectively.
Innovation Solution
An OLED driving characteristic detection circuit employing a current sensing method with a first and second current integrator, sampling capacitors, and switches to remove common noise components, allowing for precise sensing of current information and compensation for deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage sensing-based compensation method is used, then the sensing operation can be performed, but precise sensing data cannot be obtained due to large parasitic capacitor size and load dependency
Solution Approach 1:
The patent replaces the voltage sensing method with a current sensing method. Instead of measuring voltage through parasitic capacitors, the invention uses current integrators to integrate the pixel current directly, converting the measurement from voltage-based to current-based. This substitution eliminates the parasitic capacitor issue and provides more accurate sensing data.
Solution Approach 2:
The patent introduces current integrators as intermediary components between the pixel current and the sensing circuit. These integrators accumulate the pixel current over time and convert it to a voltage signal that can be measured, serving as a mediator that transforms the current information into a measurable form without requiring large parasitic capacitors.
2Measurement precision
If current sensing-based compensation method using current integrator is used, then current information can be sensed, but precise sensing data is difficult to obtain due to offset and external noise
Solution Approach 1:
The patent divides the sensing operation into multiple time periods: a first period for integrating pixel current, a second period for integrating reference current, and a third period for differential measurement. By segmenting the sensing process into distinct phases, the circuit can separately measure and then subtract offset and noise components, eliminating their effect on the final measurement.
Solution Approach 2:
The patent implements a feedback mechanism where the sensing circuit performs differential measurement by comparing the pixel current integration with a reference current integration. The offset and noise measured during the reference period are fed back and subtracted from the pixel measurement, effectively compensating for these harmful factors through feedback correction.
3Measurement precision
If multiple sensing channels are used to sense pixel current, then current information can be obtained, but common noise components affect the measurement accuracy
Solution Approach 1:
The patent uses differential measurement as a feedback mechanism to eliminate common noise. By measuring both pixel current and reference current through separate channels and then subtracting their integrations, common noise components present in both channels are cancelled out, leaving only the differential signal that represents the actual pixel characteristics.
Solution Approach 2:
The patent segments the sensing process into distinct time periods for different measurement purposes. During the first period, pixel current is integrated; during the second period, reference current is integrated; and during the third period, the differential measurement is performed. This temporal segmentation allows systematic elimination of common noise through differential measurement.
Data Source
AI summary
An organic light-emitting diode (OLED) driving characteristic detection circuit is provided. The OLED driving characteristic detection circuit comprising a first current integrator receiving a first current via a first sensing channel and outputting a first sampling voltage based on the first current, a second current integrator receiving a second current via a second sensing channel and outputting a second sampling voltage based on the second current, and a sampling circuit receiving the first and second sampling voltages, followed by storing and holding the first and second sampling voltages, and removing common noise components included in the first and second sampling voltages, a third sampling capacitor and a fourth sampling capacitor which are connected to an output terminal of the second current integrator and store and hold the second sampling voltage, and a plurality of switches which connect first ends of the first sampling capacitor to the fourth sampling capacitor.