Spatially Resolved Counter-coloring for Spectacle Lens Homogeneity

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Solution Overview

Problem

Spectacle lenses made from plastic materials often exhibit position-dependent or viewing direction-dependent color impressions due to inherent coloring, which can be distracting, especially when trying to achieve a target color like light blue but with a yellow-tinted glass material, resulting in unwanted green to blue color variations across the lens.

Innovation Solution

A method that determines the material-specific inherent color and location-dependent thickness of the lens, using a reference substrate to calculate the necessary color pigment quantities for achieving a target coloring by compensating for the inherent color effects through a color correction model, ensuring a homogeneous or gradient coloration across the lens surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If complementary colors are added to the bulk material to compensate for inherent coloring, then the color shifts towards neutral gray, but the thickness-dependent discoloration effect is retained and cannot be fully eliminated

Engineering Contradiction:
Improvecolor uniformityVSAvoidthickness-dependent discoloration
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by determining location-dependent color pigment quantities for different regions of the lens based on local thickness measurements. Instead of uniform compensation, the method calculates specific pigment amounts for each evaluation point to achieve homogeneous overall coloring despite varying thickness, directly addressing the thickness-dependent discoloration problem.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by measuring the inherent color of the lens material and determining the thickness distribution before the coloring process. This pre-analysis allows the system to calculate the required color pigment quantities in advance, compensating for thickness variations before actual coloring occurs, thereby achieving uniform color distribution.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If a wide variety of plastics and geometries are used for spectacle lenses, then design flexibility increases, but control of the resulting overall coloring becomes more difficult

Engineering Contradiction:
Improvematerial and geometry varietyVSAvoidcoloring control
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by systematically varying color pigment quantities based on lens thickness parameters at different locations. The method adjusts pigment concentration as a function of thickness, enabling precise coloring control across diverse lens geometries and materials by transforming the thickness parameter into corresponding color compensation parameters.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by using measured inherent color and thickness data to calculate location-dependent color pigment quantities. The system continuously adjusts pigment application based on feedback from thickness measurements and inherent color characterization, ensuring accurate coloring control regardless of lens geometry or material variations.

Inventive Principle:
Principle #23Feedback

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 method efficiently compensates for the inherent color effects, achieving a consistent target coloring across the entire lens surface, even with varying thicknesses and strong optical effects, effectively eliminating unwanted color deviations and ensuring precise color control.

Implementation Method 1

determining a target color pigment quantity, which deviates from the reference color pigment quantity by a color pigment quantity correction, compensating for the determined inherent color of the optical glass

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP3574292B1Spatially resolved counter-coloring
Publication Date: 2023.03.01 RODENSTOCK GMBH
  • EP3574292B1 patent drawingFigure 1
  • EP3574292B1 patent drawingFigure 2A~2C
  • EP3574292B1 patent drawingFigure 3A~3C

AI summary

The present invention relates to improved coloring of an optical glass, in particular of a spectacle lens, comprising a predetermined glass material, in order to achieve a target coloration of the optical glass. In this case, a method according to the invention comprises: determining a material-specific inherent coloration of the predetermined glass material; determining a glass thickness at a multiplicity of evaluation locations on the optical glass; ascertaining an inherent coloration of the optical glass from the material-specific inherent coloration of the predetermined glass material and the glass thickness at the multiplicity of evaluation locations on the optical glass; determining a reference color pigment amount for at least one color pigment in such a way that the reference color pigment amount applied on a reference substrate brings about for the reference substrate the target coloration to be achieved on the optical glass; defining a color correction model which describes a relationship between a deviation of a color pigment amount for at least one color pigment from the reference color pigment amount of the at least one color pigment and a resultant deviation of a coloration of the reference substrate from the target coloration; and determining a target color pigment amount which deviates from the reference color pigment amount by a color pigment amount correction which compensates for the ascertained inherent coloration of the optical glass in accordance with the defined color correction model.