Display Pixel Inspection With Monochromatic Telecentric Imaging

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Solution Overview

Problem

Existing automatic visual inspection systems for semiconductor light emitting devices in fluid environments suffer from low image definition due to chromatic aberration, high costs for aberration correction, and inflexibility in design, making precise and rapid inspection challenging.

Innovation Solution

An automatic display pixel inspection system using monochromatic light and a telecentric lens that adjusts distance based on wavelength to minimize chromatic aberration, allowing for clear image acquisition and efficient correction, and enabling flexible application across various inspection environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a general lens is used for inspection in fluid environment, then the system structure is simple, but chromatic aberration occurs causing low image definition

Engineering Contradiction:
Improvesystem structureVSAvoidimage definition
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the optical parameter by using monochromatic light instead of white light, and adjusts the lens focal length to match the wavelength of the monochromatic light. This eliminates chromatic aberration while maintaining system simplicity, achieving both clear images and structural simplicity.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a chromatic aberration-removing lens is used, then image definition is improved, but design becomes complicated and cost increases

Engineering Contradiction:
Improveimage definitionVSAvoiddesign complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the root cause of chromatic aberration by using monochromatic light instead of white light. This removes the need for complex chromatic aberration correction lenses, achieving simple design while maintaining high image definition.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the light source parameter from broadband white light to monochromatic light, and adjusts the lens focal length to match the specific wavelength. This parameter change eliminates chromatic aberration without requiring additional correction optics, reducing design complexity.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If automatic control is used for chromatic aberration correction, then image definition is improved, but cost increases

Engineering Contradiction:
Improveimage definitionVSAvoidcontrol system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the need for automatic control systems by eliminating the source of chromatic aberration through monochromatic light. This achieves high image definition without requiring complex automatic control mechanisms.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The monochromatic light source and matched focal length configuration inherently prevent chromatic aberration without requiring external control or correction mechanisms. The system is self-sufficient in eliminating optical aberrations.

Inventive Principle:
Principle #25Self-service

4Productivity

If existing inspection system is used, then inspection can be performed, but flexibility for design changes is poor

Engineering Contradiction:
Improveinspection capabilityVSAvoiddesign flexibility
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent creates a dynamic and flexible inspection system where the focal length can be adjusted to match different monochromatic light wavelengths. This allows the system to adapt to various design requirements while maintaining inspection capability.

Inventive Principle:
Principle #15Dynamics

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

The system achieves clear inspection images with minimized chromatic aberration at a lower cost and enhances flexibility, facilitating rapid and precise detection of assembly defects in semiconductor light emitting devices.

Implementation Method 1

a telecentric lens located outside the tank and configured to condense light reflected from the object irradiated with the red, green, or blue monochromatic light beam

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

a lighting device configured to irradiate the object with a red, green, and blue monochromatic light beam in a predetermined order

Methodology Applied
Scientific EffectMonochromatic light illumination: Light

Data Source

PatentEP3998474B1Automatic display pixel inspection system and method
Publication Date: 2026.02.11 LG ELECTRONICS INC
  • EP3998474B1 patent drawingFigure 1
  • EP3998474B1 patent drawingFigure 2
  • EP3998474B1 patent drawingFigure 3

AI summary

The present invention relates to an automatic display pixel inspection system and method and, particularly, to an automatic inspection system and method for inspecting defects occurring in the process of assembling semiconductor light emitting devices in a fluid.