Optical Defect Detection for Mobile Phone Displays

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Solution Overview

Problem

Existing methods for detecting defects on mirror surfaces of mobile phone displays, such as material losses, cuts, cracks, scratches, and stains, are time-consuming, tedious, and subjective, relying heavily on human experience and are not efficient.

Innovation Solution

An optical detection device with a diffuser and LED illumination system that automatically captures images of the display surface, using a camera and algorithms to analyze defects, eliminating the need for manual inspection and providing objective results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual detection method is used, then detection can be performed with simple equipment, but detection efficiency is low and it is time-consuming

Engineering Contradiction:
Improvedetection efficiencyVSAvoidequipment complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical inspection with an automated optical detection system. A camera captures images of the display surface, and image processing algorithms automatically analyze defects such as cracks, scratches, and stains. This substitution of manual mechanical detection with automated optical-mechanical systems dramatically improves detection efficiency while maintaining manageable equipment complexity through modular design.

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

Solution Approach 2:

The detection system performs self-service by automatically capturing images, processing them through algorithms, and generating detection results without requiring manual intervention for each inspection. The system autonomously identifies and classifies defects, eliminating the need for human inspectors to manually examine each display surface.

Inventive Principle:
Principle #25Self-service

2Reliability

If manual detection method is used, then equipment is simple, but detection results are subjective and depend on inspector experience

Engineering Contradiction:
Improveobjectivity of detection resultsVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces subjective human judgment with objective image processing algorithms. The camera captures standardized images under controlled lighting conditions, and computational algorithms consistently analyze pixel variations to detect defects. This eliminates subjectivity and ensures uniform detection criteria are applied across all inspections, improving reliability.

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

Solution Approach 2:

The system transforms the detection task from subjective visual assessment to objective quantitative analysis by changing parameters such as image brightness, contrast, and pixel intensity thresholds. These standardized parameter settings ensure consistent and reproducible detection results regardless of inspector variability.

Inventive Principle:
Principle #35Parameter changes

3Extent of automation

If optical detection device with diffuser and LED illumination is used, then automatic and objective detection is achieved, but device structure becomes more complex

Engineering Contradiction:
Improveautomation levelVSAvoidstructural complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The patent divides the detection device into modular segments: a diffuser module for uniform light distribution, LED illumination modules for controlled lighting, a camera module for image capture, and a processing module for analysis. Each segment performs a specific function and can be independently adjusted or replaced, making the complex system manageable and maintainable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The diffuser and LED illumination system serves multiple functions: it provides uniform lighting across the display surface, enables detection under standardized conditions, and can be adjusted for different inspection requirements. This multi-functionality reduces the need for separate specialized components, managing overall structural complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enables efficient, automatic, and objective detection of defects on mobile phone displays, reducing human error and improving inspection efficiency while allowing for easy maintenance and modification of the device.

Implementation Method 1

an opening configured to place the examined object, connected to the device by cables, in a diffuser

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

The light sources, preferably in the form of LEDs, illuminating the diffuser are placed at the sides of the diffuser

Methodology Applied
Scientific EffectLight emission from LED: Light Emitting Diode

Implementation Method 3

a camera 6 placed above... The detector is preferably a camera

Methodology Applied
Scientific EffectOptical imaging: Photography

Data Source

PatentEP3418725A1Device for optical detection of defects of mirror surfaces of flat objects, in particular the displays of mobile phones and/or smartphones
Publication Date: 2018.12.26 DIGITAL CARE SP ZOO
  • EP3418725A1 patent drawingFigure 1
  • EP3418725A1 patent drawingFigure 2
  • EP3418725A1 patent drawingFigure 3

AI summary

The invention describes a device for optical detection of defects of mirror surfaces of flat objects, in particular displays of mobile phones and/or smartphones, characterised in that in the bottom part of a housing (1) there is an opening (2) for, placed in a diffuser (10), the examined object (25) connected to the device by cables (15), whereas in an opening (3) in the top part of the housing (1) a display (3a) is placed, below which a power supply (5), a detector (6), a power stage (7) and a driver (8) are mounted, whereas illuminating means (20, 21, 22, 23, 24, 25) that illuminate the diffuser (10) are distributed at sides of the diffuser.