Lenslet Coating Uniformity via Dynamic Tilting

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Solution Overview

Problem

Existing methods for coating optical lenses with lenslets suffer from non-uniform thickness of the hard coating, leading to deformation of lenslets and uneven optical power distribution.

Innovation Solution

A method involving dipping the optical lens in a coating fluid, withdrawing it to an initial vertical position, and then tilting it to a final horizontal position before drying, ensuring a more homogeneous thickness of the hard coating across the lenslets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If dip-coating method is used to coat optical lens with lenslets, then the coating process is simple and efficient, but the thickness of the hard coating becomes non-uniform causing lenslet deformation

Engineering Contradiction:
Improvecoating process efficiencyVSAvoidcoating thickness uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies dynamic tilting of the optical lens during the drying phase of the dip-coating process. The lens is tilted at a specific angle (α) between 5° and 30° relative to the vertical position, allowing the coating fluid to redistribute uniformly under gravity while maintaining high production efficiency. This dynamic adjustment resolves the contradiction by enabling simple dip-coating to produce uniform thickness coatings.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the orientation parameter (tilt angle α) of the optical lens during processing. By adjusting the lens from a vertical position to a tilted position within the specified angle range during drying, the distribution of coating fluid is controlled to achieve uniform thickness. This parameter change allows the simple dip-coating method to overcome its inherent non-uniformity problem.

Inventive Principle:
Principle #35Parameter changes

2Loss of time

If the optical lens is kept in vertical position during drying, then the coating process is faster, but the coating thickness becomes non-uniform across the lenslet surface

Engineering Contradiction:
Improvedrying timeVSAvoidcoating thickness uniformity
Core Design Contradiction:
Loss of timeVSManufacturing precision

Solution Approach 1:

Instead of keeping the lens statically vertical during drying, the patent introduces a dynamic tilt angle adjustment. The lens is positioned at an angle α between 5° and 30° from vertical during the drying phase, which optimizes fluid distribution while maintaining reasonable drying time. This dynamic positioning resolves the time-uniformity trade-off.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent adds an angular dimension to the drying process by tilting the lens. Rather than only controlling drying time, the solution introduces orientation as an additional control parameter. This dimensional change allows simultaneous optimization of both drying efficiency and coating uniformity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the thickness tolerance of the coating layer is tightened to minimize lenslet deformation, then the optical quality improves, but the manufacturing complexity and time increase

Engineering Contradiction:
Improvelenslet shape accuracyVSAvoidcoating process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses a simple dynamic tilt adjustment during drying to achieve uniform coating thickness, avoiding the need for complex post-coating processing or sophisticated coating equipment. This straightforward dynamic modification delivers high lenslet shape accuracy without significantly increasing manufacturing complexity.

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

This approach results in a hard coating with uniform thickness, minimizing deformation of lenslets and enhancing the control of sphericity or asphericity of optical lenses, thereby improving production reliability and efficiency.

Implementation Method 1

In the initial position, that is vertically, the fluid tends to flow, under the effect of gravity, towards the lower edge of the optical lens

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 2

drying the coating fluid coating said optical lens

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP4334122B1Method for coating lenses with lenslets with an improved control on power shift
Publication Date: 2025.01.29 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP4334122B1 patent drawingFigure 1~2
  • EP4334122B1 patent drawingFigure 3~4
  • EP4334122B1 patent drawingFigure 5~6

AI summary

The disclosure relates to a method for coating an optical lens having a main surface at least partly covered with lenslets. The optical lens is dipped in a coating fluid, withdrawn to reach an initial position defined so that said main surface faces towards a first, horizontal, direction, and the coating fluid coating said optical lens is dried. After withdrawing the optical lens and before or while drying the coating fluid, the optical lens is tilted to a final position defined so that said main surface faces upwards towards a final direction having an angle comprised between 80° and 100° with respect to the first direction, the first and final directions defining a vertical plane. Alternately or in combination, while withdrawing said optical lens, part of the coating fluid is removed from the optical lens by sliding said optical lens along a mechanical blade.