Eyeglass Lens Manufacturing with Optical Insert
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Solution Overview
Problem
Existing methods for manufacturing optical displays integrated into eyeglasses suffer from optical defects near the edges due to mechanical solicitations during the casting and polishing process, and cutting through different materials (glass and plastic) poses difficulties due to their varying hardness.
Innovation Solution
The method involves molding a plastic lens blank around an optical insert with a form identical to the final lens, allowing for precise cutting in the plastic material and minimizing optical defects, while ensuring the glass insert's mechanical reference remains accessible for accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insert surface is made smaller than the final lens surface, then the mechanical solicitations during casting and polishing are reduced, but the insert edges become visible and cause optical defects in the final lens
Solution Approach 1:
The patent divides the lens manufacturing process into distinct stages: first casting the monomer with the insert, then polishing, and finally trimming. This segmentation allows each operation to be optimized independently, with trimming removing the defective edge zones created during previous operations while preserving the central optical quality.
Solution Approach 2:
The insert is positioned and fixed in the mold before the monomer is cast. This preliminary action ensures the insert remains stable and properly positioned throughout the subsequent casting and polishing operations, preventing misalignment that would cause optical defects.
2Ease of manufacture
If the insert surface is made equal to or larger than the final lens surface, then the insert extends across the entire lens providing structural support, but cutting through both glass insert and plastic material becomes difficult due to varying hardness
Solution Approach 1:
The patent extracts the difficult cutting operation by trimming only the plastic monomer material after polishing, leaving the glass insert intact and accessible. This separates the cutting task from the glass insert, avoiding the problem of cutting through materials of vastly different hardness while still achieving the final lens shape.
Solution Approach 2:
Instead of cutting through both materials simultaneously, the patent inverts the approach by first polishing the entire assembly and then trimming only the plastic portions. This reverses the conventional sequence and eliminates the difficulty of differential hardness during cutting.
3Manufacturing precision
If the insert surface is made larger than the final lens surface, then the mechanical reference of the glass insert remains accessible after trimming, but the areas of optical defects near the insert edges cannot be released
Solution Approach 1:
The patent applies local quality by creating a graduated transition zone where the monomer thickness gradually decreases from the center toward the edges of the insert. This gradual transition minimizes mechanical solicitations and optical defects at the edges while preserving the mechanical reference function of the insert.
Solution Approach 2:
The patent uses partial action by trimming the lens to a size slightly larger than the final required size, leaving a margin that includes the defective edge zones. This allows subsequent operations to remove these defective zones while maintaining the mechanical reference provided by the insert.
4Length of moving object
If a rectangular insert is used with dimensions smaller than the final lens, then the display function is achieved with small thickness, but optical defects appear in the vicinity of the insert edges during surfacing and polishing
Solution Approach 1:
The patent addresses the edge defect problem by operating in an additional dimensional space: after completing the primary casting and polishing operations, a final trimming operation is performed that removes the defective edge zones. This adds a dimensional aspect to the solution by creating and then removing a peripheral zone.
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 lens with uniform optical transmission and easy manufacturing, eliminating edge defects and material separation issues during cutting, thus providing a reliable and high-quality optical display.
Implementation Method 1
a monomer is casted into this mold
Implementation Method 2
a wave-reflecting substrate surface carried by the substrate for coupling light from a entry surface into the substrate by total reflection
Data Source
Figure 1~2C
Figure 3A~3C
Figure 3D~4
AI summary
The invention concerns a method of manufacturing a lens (1, 2) that has a front face and a rear face, and into which light beams emitted by an optical element of a light beam generator system (IB) are introduced via an entry surface (Si) and directed towards the eye of the wearer to enable information content to be viewed, by means of a transparent optical insert (IA, 2A, I) constituted by a light guide, said insert (I) being with a form substantially identical to the form of a final lens suitable for being positioned in a frame (3) of a support. According to the invention, the method comprises the following steps: manufacturing said insert (I) with a form smaller than the form of said final lens according to a proportional transformation, manufacturing a lens blank (LB) by association of plastic material forming said front face and said rear face with said insert (I) and cutting said lens blank (LB) around said insert (I) and with a distance from the edges of said insert which is around 1 mm for at least 50% of the periphery of said insert.