LED Inspection Lighting for Painted Surfaces

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Solution Overview

Problem

Existing inspection processes for painted surfaces, particularly in automotive bodies, are inefficient in terms of energy usage and defect detection, as they rely on conventional fluorescent lighting which has high energy consumption and lower efficiency compared to LED-based solutions.

Innovation Solution

The use of LED lighting fixtures with modified LED tubes that provide a calibrated set of lighting parameters, including a beam angle of at least 120 degrees, a color rendering index (CRI) of at least 90, and a color temperature of 5000° K, to create a 'zebra striped' lighting pattern for effective inspection of painted surfaces, replacing conventional fluorescent fixtures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional fluorescent lighting is used for inspection, then illumination is provided, but energy consumption is high

Engineering Contradiction:

Improveenergy consumptionVSAvoiddefect detection efficiency

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the lighting parameters by transitioning from fluorescent to LED technology, specifying a color temperature of 5000K and CRI of at least 90 to maintain optimal defect detection while achieving energy efficiency. This parameter optimization allows LED to replace fluorescent lighting without compromising inspection quality.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If conventional LED tubes with board-mounted LEDs are used, then energy efficiency is improved, but beam angle is insufficient (65-120 degrees)

Engineering Contradiction:

Improveenergy efficiencyVSAvoidbeam angle

Core Design Contradiction:

Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent employs parabolic reflectors with specific geometric curvature to redirect and expand the light beam from LED tubes. The parabolic shape focuses and distributes light to achieve a beam angle of at least 120 degrees, overcoming the inherent limitation of board-mounted LED geometry while maintaining energy efficiency.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Use of energy by moving object

If conventional LED tubes are used, then energy efficiency is improved, but color rendering index is insufficient (CRI of about 80)

Engineering Contradiction:

Improveenergy efficiencyVSAvoidcolor rendering index

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The patent specifies LED tubes with a color rendering index of at least 90 and color temperature of 5000K, representing a deliberate parameter change from conventional LED tubes (CRI ~80). This higher CRI parameter ensures accurate color representation for defect detection while maintaining the energy efficiency benefits of LED technology.

Inventive Principle:

Principle #35Parameter changes

4Use of energy by moving object

If fluorescent tubes are used, then lighting is provided, but maintenance costs and environmental impact are negative

Engineering Contradiction:

Improveenergy consumptionVSAvoidmaintenance costs

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent transitions from fluorescent tubes requiring frequent replacement and disposal to LED tubes with significantly longer operational lifetimes. Although LED tubes have higher initial cost, their extended service life reduces maintenance frequency and associated costs, aligning with the principle of replacing short-living components with longer-lasting alternatives.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 reduces energy consumption, lowers maintenance costs, and enhances defect detection efficiency while minimizing environmental impact through the use of energy-efficient LED lighting, which is more environmentally friendly and has a longer lifespan than traditional fluorescent lighting.

Implementation Method 1

The present method of inspection uses LED tubes, for instance in the T5, T8, or T12 standard tube sizes

Methodology Applied

Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 2

Light from the fluorescent tubes is reflected toward the component via polished, elongated parabolic reflectors

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS9341578B2LED-based inspection of a painted surface finish

Publication Date: 2016.05.17 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A method of inspecting a painted finish of a component such as a vehicle body or panel includes positioning the component with respect to an array of LED lighting fixtures each having LED tubes and generating light via the array with a predetermined set of lighting characteristics. The set of lighting characteristics includes a striped pattern, a beam angle of at least 120 degrees, and a CRI of at least 85 or at least 90. The method includes inspecting the painted surface for defects while illuminating the component with the light from the array. A control action is executed with respect to the component when the component contains a threshold number and/or a threshold size of the defects. Each array may have two LED tubes and four angled reflectors, and illuminating includes reflecting light from the LED tubes off of the angled reflectors toward the painted surface.