Display Controller VRR Flicker and Dimming Sync

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Display devices with variable refresh rate (VRR) functions experience flicker phenomena and mismatched local dimming, leading to suboptimal contrast ratios due to inadequate adjustment of screen refresh rates and lack of real-time control over local dimming.

Innovation Solution

A display device with a controller that adjusts the screen refresh rate based on image signals, increasing it when necessary to prevent flicker and synchronizing local dimming with the output image, using a frame rate converter to enhance the refresh rate and a backlight dimming controller to optimize lighting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the screen refresh rate is adjusted to be excessively lowered in VRR function, then power consumption is reduced, but flicker phenomenon occurs

Engineering Contradiction:

Improvepower consumptionVSAvoidflicker phenomenon

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent changes the parameter of screen refresh rate dynamically based on image signal characteristics. When the image signal has a frame rate below a threshold (e.g., 55Hz), the system increases the screen refresh rate to above the threshold to eliminate flicker, while still maintaining VRR functionality for power savings when conditions allow.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the screen refresh rate is adjusted in VRR function, then screen tearing is reduced, but local dimming becomes mismatched from output image

Engineering Contradiction:

Improvescreen tearing reductionVSAvoidlocal dimming matching

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The system implements feedback control by continuously monitoring the frame rate of incoming image signals and adjusting both the screen refresh rate and local dimming settings accordingly. This ensures that local dimming remains synchronized with the actual output image characteristics, resolving the mismatch problem while maintaining screen tearing reduction benefits.

Inventive Principle:

Principle #23Feedback

3Object-affected harmful factors

If the screen refresh rate is increased to prevent flicker, then flicker phenomenon is minimized, but image processing load increases

Engineering Contradiction:

Improveflicker phenomenonVSAvoidimage processing load

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies partial action by increasing the screen refresh rate only when necessary (i.e., when the image signal frame rate is at or below the threshold). This selective approach prevents flicker in critical situations while avoiding unnecessary image processing load during normal operating conditions, achieving a balanced solution.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11798508B2Display device and method for operating same

Publication Date: 2023.10.24 LG ELECTRONICS INC

AI summary

The present invention relates to a display device having a more improved variable refresh rate (VRR) function, and comprises: a control unit for executing a variable refresh rate (VRR) function of adjusting a screen refresh rate according to an image signal; and a display unit for outputting an image according to the screen refresh rate, wherein the control unit can increase the screen refresh rate adjusted according to the image signal.