Variable Refresh Rate Display Flicker Suppression
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Solution Overview
Problem
Implementing a variable refresh rate scheme in displays is challenging due to the potential for undesirable visible artifacts such as transient flickering when transitioning between different refresh rates, which affects power consumption and user experience.
Innovation Solution
The use of control circuitry to analyze image data and adjust a time-varying scaling factor applied by the display driver circuitry helps suppress luminance variations by adjusting the refresh rate and scaling factor during transitions between static and moving image content, minimizing flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the refresh rate is reduced to lower power consumption, then power consumption decreases, but the display may exhibit transient flickering when transitioning between refresh rates
Solution Approach 1:
The patent applies preliminary action by gradually transitioning the refresh rate from high to low (or vice versa) rather than making abrupt changes. The control circuitry increments or decrements the refresh rate by a predetermined amount over multiple frames, allowing the display to adapt smoothly and avoid transient flickering artifacts while still achieving power consumption reduction.
Solution Approach 2:
The patent implements dynamics by making the refresh rate adjustable and variable rather than fixed. The system dynamically transitions between different refresh rates based on content requirements, using incremental changes to balance power consumption efficiency with visual quality, thereby resolving the contradiction between energy savings and flicker prevention.
2Use of energy by moving object
If the refresh rate is reduced for static content, then power consumption decreases, but smooth playback of moving images is compromised
Solution Approach 1:
The patent applies dynamics by enabling the refresh rate to adapt dynamically based on content type. The control circuitry detects whether content is static or moving and adjusts the refresh rate accordingly - using lower refresh rates for static content to save power while maintaining higher refresh rates for moving images to ensure smooth playback.
Solution Approach 2:
The patent implements parameter changes by modifying the refresh rate parameter based on content characteristics. The system changes the refresh rate from high to low when transitioning to static content and vice versa, optimizing the balance between power consumption and image quality for different display scenarios.
3Device complexity
If abrupt transitions between refresh rates are made, then implementation complexity is reduced, but visible artifacts such as flickering increase
Solution Approach 1:
The patent applies preliminary action by implementing a gradual refresh rate transition mechanism that increments or decrements the refresh rate by small predetermined amounts over multiple frames. This approach adds moderate control complexity but effectively prevents visible artifacts like flickering during transitions.
Solution Approach 2:
The patent implements periodic action by applying the refresh rate changes in discrete incremental steps rather than continuously or abruptly. Each frame or set of frames uses a slightly adjusted refresh rate, creating a periodic progression that smooths the transition and eliminates visual artifacts while maintaining manageable system complexity.
Data Source
AI summary
An electronic device may have a variable refresh rate display. Static content may be displayed on the display at a lower refresh rate than moving content to conserve power. The display may include an array of pixels. Display driver circuitry in the display may load image data into rows of the pixels. The display driver circuitry may have digital-to-analog converter circuitry that supplies data signals to the array. The display driver circuitry may respond to a variable refresh rate control signal that is asserted and deasserted depending on whether static or moving image content is to be displayed. The display driver circuitry may use the digital-to-analog converter circuitry to apply a time-varying scaling factor to the image data. The magnitude of the scaling factor may be adjusted during transitions between refresh rates to help suppress luminance variations that might otherwise result in flickering on the display.