OLED Initialization Voltage Generator for Afterimage Reduction
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Solution Overview
Problem
Organic light emitting display devices face issues with power consumption and afterimage phenomena due to changes in the discharging characteristic of parasitic capacitors caused by varying voltage differences between low power voltage ELVSS and initialization voltage.
Innovation Solution
A display device with an initialization voltage generator that maintains a constant voltage difference between the variable driving voltage and initialization voltage, using a voltage generator and voltage adder to adjust the initialization voltage based on a reference voltage and local driving voltage, ensuring consistent discharging characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the low power voltage ELVSS is changed to reduce power consumption, then power consumption is reduced, but the discharging characteristic of the pixel changes causing afterimage phenomenon
Solution Approach 1:
The initialization voltage is dynamically adjusted based on the variable ELVSS voltage level to maintain a constant voltage difference. When ELVSS changes (e.g., from -2V to -4V for power saving), the initialization voltage is correspondingly adjusted (e.g., from 0V to -2V) to keep the voltage difference across the parasitic capacitor constant, thereby maintaining consistent discharging characteristics despite power consumption reduction
Solution Approach 2:
The system implements feedback control where the initialization voltage generator monitors the ELVSS voltage level and automatically adjusts the initialization voltage accordingly. This closed-loop control ensures that the voltage difference remains constant even when ELVSS varies, preventing afterimage phenomenon while allowing power consumption optimization
2Use of energy by moving object
If the voltage difference between ELVSS and initialization voltage changes, then power consumption can be reduced, but the charging time of the pixel increases causing emission response delay
Solution Approach 1:
By dynamically changing the initialization voltage parameter to match ELVSS variations, the voltage difference across the parasitic capacitor is kept constant. This ensures that the charging time and emission response speed remain unchanged even when ELVSS is adjusted for power consumption optimization
3Device complexity
If a fixed initialization voltage is used, then the circuit is simple, but afterimage phenomenon occurs when ELVSS varies
Solution Approach 1:
The initialization voltage generator is designed to dynamically adjust the initialization voltage based on ELVSS variations. This dynamic adaptation allows the system to maintain display quality consistency across different power consumption modes without requiring overly complex circuitry, achieving a balance between simplicity and reliability
Data Source
AI summary
A display device includes a display panel, a controller, a power supplier, and an initialization voltage generator. The controller generates a power control signal based on an input image. The power supplier generates a variable driving voltage that is changed based on the power control signal. The initialization voltage generator changes an initialization voltage to initialize the pixels based on the variable driving voltage.