OLED Luminance Control via Current Feedback
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Solution Overview
Problem
Conventional organic light emitting display devices face issues with maintaining desired luminance due to temperature variations and degradation of organic light emitting diodes, leading to inconsistent image quality.
Innovation Solution
The implementation of a power controller system that adjusts voltage values based on current flow through sensing resistors, using comparative values generated from full white light data to ensure consistent current supply to pixels, thereby maintaining desired luminance regardless of temperature changes and diode degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant voltage driving is used in digital driving method, then the driving circuit is simple, but the luminance varies due to temperature variations and OLED degradation
Solution Approach 1:
The patent implements a feedback mechanism where the sensing resistor monitors the actual current flowing through the OLED, and this sensed current value is fed back to the power controller. The power controller adjusts the driving voltage based on this feedback to compensate for temperature variations and OLED degradation, thereby maintaining consistent luminance while using a relatively simple circuit structure.
Solution Approach 2:
The patent replaces complex analog voltage adjustment mechanisms with a digital control system. The power controller uses digital signal processing to calculate the compensation voltage based on the sensed current and predetermined characteristics, substituting mechanical or analog adjustment systems with a more reliable digital control approach.
2Reliability
If current sensing and power adjustment system is implemented, then luminance consistency is improved, but device complexity increases
Solution Approach 1:
The patent introduces a sensing resistor as an intermediary element that indirectly measures the OLED current without requiring direct complex measurement circuits. This intermediary component simplifies the overall system by providing a straightforward way to obtain current information for feedback control.
Solution Approach 2:
The power controller dynamically adjusts the driving voltage parameter based on the sensed current and predetermined OLED characteristics. By changing the voltage parameter in real-time according to actual operating conditions, the system maintains consistent luminance output while using a manageable level of system complexity.
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 allows for the display of images with consistent luminance by controlling the current flow to pixels, effectively mitigating the effects of temperature variations and diode degradation, ensuring stable image quality.
Implementation Method 1
a sensing resistor coupled between the power supply and the power line
Implementation Method 2
the organic light emitting display device displays images by using organic light emitting diodes (OLEDs) that emit light through recombination of electrons and holes
Data Source
AI summary
An organic light emitting display device and a method of driving the same. The organic light emitting display device includes a scan driver, a data driver for supplying data signals, and pixels. Each of the pixels is configured to control whether or not a current flows from a first power to a second power both coupled to the pixels, the current corresponding to a corresponding one of the data signals. A power supply is included for supplying the first power to a power line coupled to the pixels. A sensing resistor is coupled between the power supply and the power line. A power controller is provided for controlling the power supply to adjust a voltage value of the first power for controlling an amount of current that flows through the sensing resistor to be substantially equal to an amount of current corresponding to data of a current frame.