Display Defect Detection Using Diffuse Reflection to Filter Smudges

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing display defect detection methods for LCDs are inefficient due to the need for a dedicated cleaning phase to reduce erroneous detection, which decreases detection speed and affects efficiency.

Innovation Solution

A display defect detection method and apparatus that uses a diffuse reflection light source to differentiate between actual display defects and external smudges by capturing images in both a solid-color and die-out state, allowing for automatic differentiation and eliminating the need for a cleaning phase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dedicated cleaning phase is added before image shooting to remove smudges, then erroneous detection probability is reduced, but detection speed and efficiency decrease

Engineering Contradiction:
Improvedetection accuracyVSAvoiddetection efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent extracts and removes the harmful cleaning phase from the detection process. Instead of physically cleaning the screen, the system uses image processing algorithms to identify and filter out smudge-related artifacts from captured images, thereby maintaining detection accuracy without sacrificing efficiency

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical cleaning operation with an optical-imaging-based detection system combined with digital image processing. The diffused reflection light source illuminates the screen to make smudges visible, and software algorithms automatically distinguish smudges from actual display defects, eliminating the need for manual or mechanical cleaning

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If manual cleaning is performed by skilled persons to remove smudges, then detection accuracy improves, but detection time increases

Engineering Contradiction:
Improvedefect detection precisionVSAvoidcleaning time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs self-service by automatically detecting and distinguishing smudges from actual defects through image processing algorithms. The diffused reflection lighting combined with computational algorithms enables the system to self-correct for smudge interference without requiring external manual intervention or cleaning operations

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the illumination parameter by introducing a diffused reflection light source that specifically enhances the visibility of surface contaminants while maintaining the ability to detect subsurface defects. This parameter change enables automatic differentiation between smudges and actual defects through image analysis

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly improves detection speed and efficiency by accurately distinguishing between display defects and smudges, reducing erroneous detection and eliminating the requirement for manual cleaning, thereby enhancing the overall detection process.

Implementation Method 1

a diffuse reflection light source is configured to provide a diffuse reflection light source

Methodology Applied
Scientific EffectDiffuse reflection: Reflection

Implementation Method 2

when an external smudge such as dust or a fingerprint is attached on the front side of the tested LCD, erroneous detection may be caused

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP3361239B1Display defect detection method, device and equipment
Publication Date: 2022.09.28 HUAWEI TECH CO LTD
  • EP3361239B1 patent drawingFigure 1A~1B
  • EP3361239B1 patent drawingFigure 2
  • EP3361239B1 patent drawingFigure 3A

AI summary

The present invention discloses a display defect detection method, apparatus, and device for a display screen. The method includes: identifying a suspected defective pixel from a first image of a front side of a tested display screen, where the first image is shot when the tested display screen is in a solid-color display state; identifying an external smudgy pixel from a second image of the front side of the tested display screen, where the second image is shot when the tested display screen is in a die-out state and the front side is illuminated by a diffuse reflection light source; detecting, for each suspected defective pixel identified from the first image, whether a pixel at a same location in the second image is the external smudgy pixel; and if no, determining the suspected defective pixel as a display defective pixel.