Inkjet Tinting of Spectacle Lenses With Combined Layer Curing
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Solution Overview
Problem
Existing methods for tinting spectacle lenses, such as dye baths, are inefficient, hazardous to workers, energy-intensive, and lack reproducibility, leading to inconsistent color density and optical quality issues like haze and scattering.
Innovation Solution
An inkjet printing method involving multiple layers of inkjet printing inks with controlled coalescence and curing, allowing for precise application of color gradients and uniform thickness to achieve consistent color density and optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dye bath method is used to tint spectacle lenses, then the lenses can be tinted with color, but the process requires high temperature (90-100°C) and prolonged time (minutes to hours), leading to significant energy consumption and worker exposure to hazardous organic solvents
Solution Approach 1:
The patent replaces the thermal-diffusion mechanism of dye bath tinting with a direct deposition mechanism using inkjet printing technology. The inkjet system deposits tinting material directly onto the lens surface through controlled droplet ejection, eliminating the need for high-temperature thermal processing and prolonged soaking times, thereby significantly reducing energy consumption while maintaining consistent color density
Solution Approach 2:
The patent changes the fundamental processing parameters from high temperature (90-100°C) and long duration (minutes to hours) to ambient or mild temperature conditions with rapid deposition (seconds). The inkjet printing process allows precise control of deposition parameters such as droplet size, spacing, and layering, enabling consistent color density without requiring extreme thermal or temporal parameters
2Reliability
If a dye bath method is used to tint spectacle lenses, then the lenses can be tinted, but the process requires high boiling point organic solvents (e.g., benzyl alcohol) which pose health risks to workers
Solution Approach 1:
The patent substitutes the liquid-phase dye bath immersion process with a controlled droplet deposition system. The inkjet printing mechanism ejects precise amounts of tinting material directly onto the lens surface, eliminating the need for large volumes of hazardous organic solvents and thereby protecting worker health while maintaining tinting quality
Solution Approach 2:
The patent employs water-based or low-toxicity ink formulations that can be precisely deposited and rapidly cured, replacing the need for persistent, high-boiling-point organic solvents. These alternative formulations achieve the desired tinting effect without requiring hazardous chemical carriers, thus reducing worker exposure risks
3Reliability
If a dye bath method is used to tint spectacle lenses, then the lenses can be tinted, but the process leads to significant vaporization of organic solvent and water, requiring collection and replenishment which increases costs
Solution Approach 1:
The patent replaces the vapor-intensive thermal drying process with a controlled curing mechanism. The inkjet-deposited layers are cured through UV irradiation or other non-thermal methods, eliminating the need for high-temperature evaporation and thereby preventing significant vaporization of solvents and water, reducing material loss and associated costs
Solution Approach 2:
The patent changes the drying/curing parameter from high temperature thermal evaporation to ambient or mild temperature chemical curing. This parameter change allows the tinting material to set and harden without requiring energy-intensive heating that would cause vaporization, thus conserving materials and reducing replenishment costs
4Reliability
If a porous ink receptive coating is used for inkjet printing, then the dye can penetrate into the coating, but the dyes are not fixed and can move during subsequent processes like overcoating, leading to ink bleeding and poor resolution control
Solution Approach 1:
The patent applies a preliminary treatment to the lens surface that creates optimal adhesion properties before inkjet deposition. This pre-treatment ensures that the deposited ink layers are firmly anchored to the substrate, preventing subsequent migration or bleeding during overcoating processes while maintaining the desired penetration and color saturation
Solution Approach 2:
The patent employs a composite surface structure combining a primer layer with specific adhesion properties and the tinting ink layer. This composite approach ensures strong bonding between the ink and substrate while maintaining resolution control, preventing the ink from migrating during subsequent processing steps
5Reliability
If multiple layers of inkjet printing ink are applied with overlapping, then the color density can be enhanced, but the layers need to be cured separately which increases process time
Solution Approach 1:
The patent merges multiple curing operations into a single combined curing step. By designing the inkjet ink formulation and layer structure to allow simultaneous curing of multiple overlapping layers, the process eliminates sequential curing wait times, reducing total process time while maintaining the enhanced color density achieved through multiple layers
Solution Approach 2:
The patent enables continuous processing by eliminating idle curing intervals between layers. The inkjet system can deposit multiple layers in rapid succession, and the curing process can be continuously applied to all layers simultaneously or in overlapping sequences, maintaining productive action throughout the process rather than having stop-and-go curing cycles
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 method provides a cost-effective, time-efficient, and safe process for tinting spectacle lenses with reproducible color gradients and minimal optical distortion, enhancing transparency and reducing scattering.
Implementation Method 1
droplets of at least a first inkjet printing ink (PI1) to form at least a first layer (L1) and printing droplets of at least a second inkjet printing ink (PI2) to form at least a second layer (L2)
Implementation Method 2
curing said at least first layer (L1) and said at least second layer (L2) together in a combined curing step
Data Source
Figure 1a~1d
Figure 2~3
Figure 4a~4e
AI summary
The present invention is directed to an ink jet printing method of tinting a spectacle lens substrate comprising the steps: (a) providing a spectacle lens substrate having a front surface and a back surface, wherein said spectacle lens substrate can be precoated, (b) printing droplets of at least a first inkjet printing ink (P11) to form at least a first layer (L1) and droplets of at least a second inkjet printing ink (P12) to form at least a second layer (L2) on at least one of said front surface and back surface, wherein at least one of said at least first inkjet printing ink (P11) and said at least second inkjet printing ink (P12) is colored, said at least first layer (L1) and said at least second layer (L2), each covering fully or partially at least one of said front surface and back surface, forming a stack which covers at least one of said front surface and back surface, wherein said at least first layer (L1) and said at least second layer (L2) are at least partially overlapping in said stack, (c) curing said at least first layer (L1) and said at least second layer (L2) together in a combined curing step. Moreover the invention is directed to a tinted spectacle lens having a front surface and a back surface wherein said tinted spectacle lens comprises a color design on at least one of said front surface and back surface, said color design is selected from the group consisting of a non-linear color gradient, contoured di- or polychromatic pattern, contoured di- or polychromatic figure, di- or polychromatic alphabetic code, di- or polychromatic numerical code, di- or polychromatic alphanumerical code, and combinations thereof.