OLED Panel Driver Frame Frequency Control for Flicker Prevention
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Solution Overview
Problem
In OLED display devices, adaptive sync modes can lead to flicker and luminance changes due to varying frame frequencies, especially when using impulsive driving methods, which affect image quality and user perception.
Innovation Solution
The OLED display device employs a panel driver that adjusts the frame frequency by changing the number of emission periods within a frame period, maintaining a constant emission duty ratio and adjusting gamma sets based on input image data availability, thereby preventing flicker and luminance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive sync mode is applied to allow variable frame rate, then tearing phenomenon is reduced, but flicker occurs and luminance change is perceived
Solution Approach 1:
The patent applies periodic action by maintaining a fixed relationship between frame periods and emission periods. The display panel is driven at a frame frequency that is 1/N of the emission frequency, ensuring that each frame period contains an integer number of emission periods. This periodic structure allows the emission duty ratio to remain constant even when frame rate varies, thereby preventing flicker while enabling adaptive sync mode to eliminate tearing.
2Adaptability or versatility
If frame frequency is changed to match variable frame rate, then synchronization is improved, but emission duty ratio varies causing flicker
Solution Approach 1:
The patent employs parameter changes by adjusting the frame frequency to be exactly 1/N of the emission frequency, where N is a positive integer. This specific parameter relationship ensures that when frame rate changes occur, the emission duty ratio remains constant because each frame period consistently contains an integer number of emission periods. The panel driver dynamically adjusts the frame frequency while maintaining this 1/N relationship, achieving both adaptability and stability.
3Use of energy by moving object
If impulsive driving method is used for periodic light emission, then power efficiency is improved, but flicker occurs under adaptive sync mode
Solution Approach 1:
The patent implements feedback by having the panel driver continuously monitor the relationship between frame periods and emission periods. When adaptive sync mode is activated and frame rate varies, the panel driver adjusts the frame frequency to maintain the 1/N relationship with emission frequency. This feedback mechanism ensures that the emission duty ratio remains constant, preventing flicker while preserving the power efficiency benefits of impulsive driving.
Data Source
AI summary
An organic light emitting diode (OLED) display device includes a display panel including a plurality of pixels, and a panel driver configured to drive the display panel. The panel driver drives the display panel at a frame frequency corresponding to 1/N of an emission frequency such that each frame period corresponds to an N multiple of an emission period, where N is an integer greater than 1. The panel driver gradually decreases the frame frequency of the display panel in a case where input image data are not received and gradually increases the frame frequency of the display panel in a case where the input image data are received.