Ophthalmic Lens Orientation Inspection with Adaptive Thresholding
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Solution Overview
Problem
Existing methods for determining the orientation and inversion states of contact lenses in automated production processes are unreliable due to fixed thresholds that do not account for variations in temperature, raw material batches, or lens design, leading to incorrect sorting and customer dissatisfaction.
Innovation Solution
A method and system that dynamically adapt orientation and inversion threshold values based on the distribution of previous lens inspections, ensuring accurate determination of lens orientation and inversion states by using imaging and processor analysis to adjust thresholds in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed threshold values are used for determining orientation and inversion states, then the inspection process is simple and fast, but the determination accuracy decreases due to variations in temperature, raw material batches, or lens design
Solution Approach 1:
The patent implements dynamic threshold adaptation where the threshold values for orientation and inversion determination are continuously adjusted based on the distribution of measured values from previous inspections. The system automatically updates thresholds to match current production conditions, transforming static fixed thresholds into dynamic adaptive thresholds that respond to variations in temperature, raw material batches, and lens design.
Solution Approach 2:
The system employs feedback mechanisms by analyzing the distribution of orientation and inversion values from previously inspected lenses and using this information to adjust subsequent threshold values. This closed-loop feedback ensures that the thresholds remain optimized for current production conditions, improving determination accuracy without requiring manual intervention.
2Productivity
If fixed thresholds are used throughout the production run, then the device operation is simple, but incorrect sorting and re-orientation/re-inversion occur due to process variations
Solution Approach 1:
The system dynamically adapts threshold values during the production run based on the distribution of measured orientation and inversion values. This allows the inspection system to maintain high sorting accuracy despite variations in temperature, raw material batches, or lens design, preventing incorrect sorting and unnecessary re-orientation/re-inversion operations.
Solution Approach 2:
By continuously analyzing the distribution of inspection values and adjusting thresholds accordingly, the system maintains high reliability in sorting decisions throughout the production run. The feedback mechanism ensures that only lenses that truly fail to meet quality standards are sorted out, maximizing production yield while maintaining accuracy.
3Measurement precision
If dynamic threshold adaptation is implemented, then the determination accuracy improves, but the computational complexity and processing time increase
Solution Approach 1:
The system applies partial adaptation by updating thresholds based on a selective sample of previously inspected lenses rather than requiring complete data sets. This approach provides sufficient accuracy improvement while minimizing the computational overhead and processing time penalty associated with full dynamic adaptation.
Data Source
AI summary
A method for optically inspecting an ophthalmic lens in an automated lens production process to determine an orientation state and an inversion state of the ophthalmic lens. The method comprises the steps of acquiring an image of the ophthalmic lens, determining from the acquired image an orientation value of the lens, comparing the determined orientation value with an orientation threshold value, and determining that the lens is oriented right side up when the determined orientation value is higher than the orientation threshold value, or determining that the lens is oriented upside down when the determined orientation value is lower than the orientation threshold value, or vice versa.