OLED Display Driving Circuit for Threshold Voltage Deviation Compensation
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Solution Overview
Problem
Active matrix OLED displays face issues with non-uniform luminance and contrast due to threshold voltage deviations among driving transistors, leading to luminance uniformity failures and gray/white level discrepancies between pixels and panels.
Innovation Solution
An OLED display system that includes a signal controller generating display gamma control data and offset gamma control data based on threshold voltage deviations, with a data driver selecting and combining display gray voltages and offset gray voltages to compensate for these deviations, ensuring uniform luminance across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If active matrix OLED display uses driving transistor to control current, then luminance control is achieved, but threshold voltage deviation causes luminance uniformity failure
Solution Approach 1:
The patent measures and stores threshold voltage values of driving transistors before normal display operation. This preliminary characterization allows the system to compensate for threshold voltage deviations during operation by selecting appropriate gray voltage levels from pre-defined sets, thereby achieving luminance uniformity across the display panel.
Solution Approach 2:
The patent changes the voltage level parameters of gray voltages based on measured threshold voltage deviations. By maintaining a first set of gray voltages for normal operation and a second set with adjusted voltage levels for compensation, the system adapts the electrical parameters to counteract transistor variations and achieve uniform luminance.
2Measurement precision
If optical compensation method is applied to correct data signal, then gamma characteristics are improved, but threshold voltage deviation between panels still causes luminance and contrast ratio non-uniformity
Solution Approach 1:
The patent implements a feedback mechanism where threshold voltage values of driving transistors are measured and stored. Based on this feedback information, the system selectively applies different gray voltage sets to compensate for panel-specific variations, thereby achieving both gamma correction and luminance uniformity across different panels.
Solution Approach 2:
The system performs preliminary measurement and storage of threshold voltage characteristics for each panel during manufacturing or initialization. This preliminary action enables subsequent compensation operations to address between-panel variations in luminance and contrast ratio.
3Manufacturing precision
If additional signal wires or transistors are used to compensate for threshold voltage deviation, then luminance uniformity can be improved, but device complexity increases
Solution Approach 1:
The patent creates virtual compensation signals by selecting from pre-defined sets of gray voltages based on measured threshold voltage values. Instead of adding physical compensation circuits, the system uses data processing and voltage selection to achieve compensation, thereby avoiding increased device complexity while improving luminance uniformity.
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 threshold voltage deviations, achieving uniform luminance and contrast across the display panel without requiring additional signal wires or transistors, thereby improving the display's overall performance.
Implementation Method 1
an organic light emitting diode (OLED) display using an organic light emitting element
Data Source
AI summary
An organic light emitting diode (OLED) display and a method of driving the same are provided. The OLED display includes a display panel including data lines, scan lines, and pixels that are connected to a corresponding data line and a corresponding scan line; a signal controller that generates display gamma control data corresponding to a display grayscale of an image source signal according to previously stored gamma curve information and that generates offset gamma control data corresponding to a position of each pixel according to threshold voltage deviation information; a scan driver that supplies scan signals to the scan lines; and a data driver that generates data signals according to the display gamma control data and the offset gamma control data and that supplies signals to the data lines.