Initial Signal Generator for Low-Frequency OLED Anode Reset
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Solution Overview
Problem
Existing OLED display panels experience flickering and brightness inconsistencies during low-frequency driving due to voltage fluctuations and threshold voltage drift in the pixel drive circuit, particularly in low brightness conditions.
Innovation Solution
Implementing a low frequency driving mode with a refresh frame stage and a hold frame stage, utilizing an initial signal generator to determine anode reset voltages based on current display brightness values and average picture levels, and dynamically adjusting these voltages to balance voltage fluctuations across different gray scales.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low frequency driving mode is used to reduce power consumption, then energy efficiency is improved, but flickering and brightness inconsistencies occur due to voltage fluctuations and threshold voltage drift
Solution Approach 1:
The patent segments the low frequency driving mode into two distinct frame stages: refresh frame stage for writing data and hold frame stage for holding data with anode reset voltage application. This segmentation allows different operations to be performed at different times, reducing flickering while maintaining low power consumption during the hold stage.
Solution Approach 2:
The patent applies preliminary action by resetting the anode voltage to an initial value during the hold frame stage before the next refresh cycle. This preliminary reset action compensates for threshold voltage drift and residual charges that would otherwise cause brightness inconsistencies and flickering in subsequent frames.
2Reliability
If anode reset voltage is applied during hold frame stage, then flickering is reduced, but device complexity increases due to additional signal generation and control
Solution Approach 1:
The initial signal generator is designed to serve multiple functions: it generates both the anode reset voltage signals and the data signals for the pixel circuits. This multi-functionality reduces the need for separate dedicated reset voltage generation circuits, thereby limiting the increase in device complexity while still achieving flicker reduction.
Solution Approach 2:
The patent changes the voltage parameter dynamically by applying different anode reset voltages based on the display brightness value and average picture level. This parameter adaptation allows the system to maintain display uniformity across different brightness conditions without requiring complex fixed-voltage circuitry for each scenario.
3Measurement precision
If display brightness value is considered for anode reset voltage determination, then brightness accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent uses the display brightness value as a key parameter to determine the anode reset voltage, creating a direct relationship between brightness level and reset voltage magnitude. This parameter-based approach simplifies the control logic compared to more complex algorithms, as the brightness value directly guides the voltage selection without requiring extensive calculations.
Solution Approach 2:
The system implements feedback by using the display brightness value (which reflects the actual display state) to adjust the anode reset voltage in subsequent frames. This feedback mechanism improves brightness accuracy over time while keeping the processing relatively simple, as it relies on comparing the current brightness with target values and making corresponding voltage adjustments.
Data Source
AI summary
The display panel includes multiple pixel units arranged in an array, a pixel unit including multiple sub-pixels, a sub-pixel including a pixel drive circuit and a light emitting element connected with the pixel drive circuit, the display panel further including an initial signal generator, the display panel including a low frequency driving mode and a normal driving mode, the low frequency driving mode including a refresh frame stage for writing data to the pixel unit and a hold frame stage for holding the data written to the pixel unit, the initial signal generator being configured to acquire a current display brightness value band and a pattern to be displayed in the low frequency driving mode; quantize the pattern to be displayed to get an average picture level; determine a corresponding anode reset voltage according to the current display brightness value band and the average picture level.