OLED Impedance Detection Circuit with Dynamic Voltage Modulation
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Solution Overview
Problem
The existing organic light emitting diode (OLED) display devices face challenges in accurately measuring the impedance of light emitting diodes due to their differences in materials, formation conditions, and driving voltages, leading to difficulties in detecting exact degradation and compensating for data signals, which results in luminance variations and afterimages.
Innovation Solution
An OLED display device with an impedance detection part comprising a sensing circuit, input control part, and analog-to-digital converter (ADC) is implemented, where the input control part modulates the sensing voltage using Zener diodes and operational amplifiers to ensure the measured impedance falls within the ADC's effective measurement range, allowing for accurate impedance calculation and compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance measurement is performed using a standard ADC, then the measurement process is simple, but the measurement precision is insufficient due to limited ADC range and variations in LED characteristics
Solution Approach 1:
The patent applies dynamics by making the measurement circuit adaptable through switching between different voltage sources (first voltage source for high impedance, second voltage source for low impedance) based on the actual impedance level of the OLED. This dynamic adjustment allows the circuit to optimize its measurement range for different LED characteristics, thereby improving measurement precision without requiring a single complex high-range ADC
Solution Approach 2:
The patent changes the voltage parameter dynamically by selecting different voltage sources depending on the impedance magnitude. When impedance is high, a lower voltage source is used; when impedance is low, a higher voltage source is used. This parameter change strategy enables accurate impedance measurement across varying OLED degradation states while keeping the ADC within its effective measurement range
2Adaptability or versatility
If a fixed voltage measurement method is used, then the circuit is simple, but it cannot accurately measure both degraded and non-degraded LEDs with different impedance ranges
Solution Approach 1:
The measurement circuit is designed to dynamically switch between different voltage sources based on the impedance level of the OLED being measured. This dynamic configuration allows the same circuit to adapt to both degraded LEDs (higher impedance) and non-degraded LEDs (lower impedance), providing versatile measurement capability without requiring multiple dedicated measurement circuits
Solution Approach 2:
The measurement process is segmented into different ranges: high impedance range measured with first voltage source and second ADC, low impedance range measured with second voltage source and first ADC. This segmentation allows each measurement path to be optimized for its specific range, improving overall measurement adaptability across different LED degradation states
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
This solution enables precise measurement and compensation of light emitting diode degradation, improving image quality by adjusting the data signal to account for variations in impedance, thereby reducing afterimages and maintaining consistent luminance across sub-pixels.
Implementation Method 1
the input control part modulates the sensing voltage using Zener diodes and operational amplifiers
Data Source
AI summary
An organic light emitting diode display device includes a display panel including a plurality of sub-pixels, each of which includes a driving thin film transistor and a light emitting diode; and an impedance detection part connected to the plurality of sub-pixels of the display panel. The impedance detection part includes a sensing circuit part, an input control part, and an analog-to-digital converter. The input control part generates a modulated output by modulating an output of the sensing circuit part and inputs the modulated output to the analog-to-digital converter.