Display Pulse Density Mapping for PWM Artifact Mitigation

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Solution Overview

Problem

Displays using pulse width modulation (PWM) for color mixing can cause visual artifacts such as color breakup and motion blur due to inconsistent light persistence across different color channels, leading to streaking and false contouring when a user's eye moves during frame transitions.

Innovation Solution

Implementing pulse density mapping (PDM) to distribute light within a frame proportionally across color channels, maintaining ratios and subdividing frames into subframes or sub-pulses to reduce visual artifacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If pulse width modulation (PWM) is used for color mixing, then color mixing capability is improved, but visual artifacts such as color breakup and motion blur occur

Engineering Contradiction:

Improvecolor mixing capabilityVSAvoidvisual artifacts

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the frame into multiple subframes (e.g., first subframe, second subframe) and further segments each subframe into multiple sub-pulses. This segmentation allows different color channels to be activated at different times within the frame, enabling precise color mixing while eliminating the harmful visual artifacts caused by traditional PWM methods.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs periodic pulsing within each subframe, where multiple sub-pulses are distributed across the subframe duration. This periodic action pattern allows light to be turned on and off multiple times within a single frame, maintaining color mixing capability while reducing motion blur and color breakup artifacts through more uniform light distribution.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If PWM is used to control pixel brightness, then brightness control precision is improved, but light persistence becomes inconsistent across color channels

Engineering Contradiction:

Improvebrightness control precisionVSAvoidlight persistence consistency

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent applies different pulse distributions to different color channels within the same subframe. Each color channel can have its own optimized pulse timing and duration, allowing precise brightness control for each channel while maintaining consistent light persistence characteristics across all channels, thereby eliminating the inconsistency problem of traditional PWM.

Inventive Principle:

Principle #3Local quality

3Speed

If frame rate is increased to reduce motion blur, then motion clarity is improved, but reprojection errors increase during frame transitions

Engineering Contradiction:

Improveframe rateVSAvoidreprojection accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent performs preliminary action by distributing light uniformly throughout the frame using multiple sub-pulses before the frame transition occurs. This preliminary uniform distribution stabilizes the displayed image and reduces reprojection errors that would otherwise occur during frame transitions, even when operating at high frame rates.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250356805A1Display artifact mitigation using pulse density mapping

Publication Date: 2025.11.20 META PLATFORMS TECHNOLOGIES LLC

AI summary

The disclosed computer-implemented method may include receiving a pulse width value corresponding to a pulse for activating a pixel of a color channel for a frame and dividing the pulse into a plurality of sub-pulses. The method may also include activating the pixel for the frame based on the plurality of sub-pulses. Various other methods, systems, and computer-readable media are also disclosed.