Foldable Display Refresh Rate Sequencing for Strain Artifacts

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Solution Overview

Problem

Foldable displays experience perceivable image artifacts due to shifting threshold voltages of transistors during display strain transition events, such as unfolding or folding, leading to brightness variations and luminance glitches.

Innovation Solution

Implement a frame rate insertion and sequencing technique that temporarily increases the refresh rate during display strain transition events to compensate for shifting threshold voltages, followed by a gradual reduction to a lower refresh rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the refresh rate is reduced to save power, then energy consumption decreases, but image artifacts become more perceivable due to threshold voltage shifts during folding events

Engineering Contradiction:

Improvepower consumptionVSAvoiddisplay quality

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies dynamic refresh rate adjustment by transitioning from a static low refresh rate to a variable refresh rate that temporarily increases during folding events. The system dynamically selects between a first refresh rate (lower) for normal operation and a second refresh rate (higher) during strain transitions, optimizing both power consumption and display quality based on real-time conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the refresh rate parameter in response to detected folding events. When a folding event is detected, the system transitions from displaying frames at a first refresh rate to a second refresh rate, thereby adjusting the temporal parameter of frame updates to compensate for threshold voltage shifts and eliminate image artifacts

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the refresh rate is increased to eliminate image artifacts, then display quality improves, but power consumption increases

Engineering Contradiction:

Improvedisplay qualityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic high refresh rate updates only during specific folding events rather than continuously. The system detects folding events and triggers increased refresh rate temporarily, then returns to the lower refresh rate, creating a periodic pattern of high-quality updates that maintains display quality during critical moments while conserving power during normal operation

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies excessive action by temporarily exceeding the normal refresh rate requirement during folding events. Instead of maintaining a constantly high refresh rate, the system applies a higher second refresh rate only partially during detected folding events, providing more than enough updates to compensate for threshold voltage shifts while avoiding continuous excessive power consumption

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20260065824A1Display Strain Aware Frame Insertion Frame Rate Sequencing

Publication Date: 2026.03.05 APPLE INC

AI summary

An electronic device may include an electronic display to display frames of image data and processing circuitry to determine a display strain transition event of the electronic display and change a refresh rate of the electronic display based on the determination of the display strain transition event. The electronic device may temporarily increase the refresh rate based on determining that the display strain transition event includes folding or unfolding the electronic display. The electronic device may sequence down the refresh rate to a lower refresh rate after a period of time. As such, perceivable image artifacts in displayed image content caused by folding or unfolding the electronic display may be reduced or eliminated.