Variable Refresh Display Emission Control for Flicker-Free Luminance
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Solution Overview
Problem
Display devices operating at variable refresh rates experience luminance deviations and flicker due to hysteresis characteristics of the driving transistor, particularly when transitioning between high and low frequencies, which can lead to undesirable visual artifacts like flicker.
Innovation Solution
A controller in the display device omits cycle differential driving operations when the frequency difference exceeds a threshold, and adjusts the lengths of emission periods in frames, and adjusts the emission periods in frames, thereby reducing luminance deviations and preventing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If cycle differential driving is performed to compensate for luminance decrease during low-frequency driving, then luminance is maintained, but luminance deviation is aggravated when transitioning from high frequency to low frequency
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the emission period length based on the current driving frequency. When the driving frequency is lower than the threshold frequency, the emission period is extended to compensate for luminance decrease. When the driving frequency is higher than or equal to the threshold frequency, the emission period is reduced to the standard length, preventing luminance deviation during frequency transitions. This dynamic parameter adjustment resolves the contradiction between maintaining luminance and preventing luminance deviation.
2Illumination intensity
If emission period length is extended to compensate for luminance decrease, then luminance is maintained, but flicker occurs during frequency transitions
Solution Approach 1:
The patent implements dynamics by making the emission period length adaptive to the current driving frequency. The emission period is dynamically adjusted based on real-time frequency detection: extended when frequency is low to maintain luminance, and reduced to standard length when frequency is high to eliminate flicker. This dynamic adaptation allows the system to maintain luminance while preventing flicker during frequency transitions.
3Use of energy by moving object
If variable refresh rate is implemented to improve power efficiency, then power consumption is reduced, but luminance deviation and flicker occur
Solution Approach 1:
The patent applies parameter changes by introducing frequency-based control of emission period length. When the display operates at variable refresh rates below the threshold frequency, the emission period is extended to compensate for luminance decrease and prevent flicker. When the refresh rate is at or above the threshold frequency, the emission period returns to standard length. This parameter adjustment maintains power efficiency benefits while eliminating luminance deviation and flicker issues.
Data Source
AI summary
A display device includes a display panel including a plurality of pixels. The display device displays an image at a variable driving frequency. The display device further includes an emission driver which provides an emission signal to the pixels, and a controller which performs a cycle differential driving operation in which lengths of emission periods defined by the emission signal gradually increase in a frame. The controller omits the cycle differential driving operation when a change in the variable driving frequency corresponds to a frequency difference that is greater than or equal to a threshold frequency difference.