Contact Lens Orientation Detection Using Shallow Depth of Field
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Solution Overview
Problem
Existing contact lens inspection methods in automated manufacturing lines fail to accurately and reliably detect upside-down oriented contact lenses, which hinders quality evaluation and requires additional reorientation steps.
Innovation Solution
A camera system with a depth of field up to 70% of the sagittal height is used to determine image defocus and noise, comparing these parameters with thresholds to identify proper orientation, employing techniques like Wiener filters and Fourier transforms for image analysis, and utilizing bright or dark field imaging units to produce orthographic images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If image blurriness or reflection/refraction methods are used to detect contact lens orientation, then detection capability is provided, but reliability and accuracy in detecting upside-down oriented lenses remain insufficient
Solution Approach 1:
The patent utilizes focus-induced image quality changes (analogous to color/appearance changes) to detect lens orientation. When the lens is properly oriented, the curvature creates a specific focus pattern; when upside-down, the focus pattern changes detectably. This allows reliable and accurate orientation detection through image analysis.
2Measurement precision
If complex inspection methods are implemented to improve detection accuracy, then measurement precision improves, but device complexity and integration difficulty increase
Solution Approach 1:
The patent replaces complex mechanical or manual orientation detection methods with an optical-imaging-based system. By using a camera to capture images and analyzing focus patterns through image processing algorithms, the system achieves accurate orientation detection with simpler, more automated equipment that integrates easily into existing manufacturing lines.
3Ease of manufacture
If traditional inspection parameters are used for properly oriented lenses, then evaluation is simplified, but detection of upside-down lenses cannot be performed and additional reorientation measures are required
Solution Approach 1:
The patent performs orientation detection as a preliminary step before quality evaluation. By detecting lens orientation first using image focus analysis, the system can automatically identify upside-down lenses and trigger reorientation measures before the main inspection process, preventing evaluation errors and reducing waste.
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 enables reliable and efficient identification of upside-down contact lenses, ensuring accurate quality assessment and integration into automated manufacturing lines for comprehensive inspection, including size, surface defects, and cosmetic evaluations.
Implementation Method 1
providing a camera system having a depth of field of up to 70%, particularly up to 50%, more particularly up to 40% of the sagittal height
Implementation Method 2
GB2433782 A discloses a method and system for determining the right-side up or upside-down orientation of a contact lens based on a reflected or refracted image
Implementation Method 3
GB2433782 A discloses a method and system for determining the right-side up or upside-down orientation of a contact lens based on a reflected or refracted image
Data Source
Figure 1a~2b
Figure 3
AI summary
A method for determining the orientation of a contact lens (1) on a lens support (3) comprises the steps of: • - providing a contact lens (1) having a lens center (2) and a sagittal height (h), • - providing a lens support (3), • - arranging the contact lens (1) on the lens support (3), • - providing a camera system (40) having a depth of field (4) of less than the sagittal height (h), • - illuminating the contact lens (1) arranged on the lens support (3) with a light beam, • - focusing the camera system (40) to a set focus corresponding to the expected position of the lens center (2) of the properly oriented contact lens (1) arranged on the lens support (3) with the lens center (2) of the properly oriented contact lens (1) on the lens support (3) being within the depth of field (4) of the focused camera system (40), • - producing an image (10) of the contact lens (1), • - scanning the image (10) of the contact lens (1) in at least one image portion (S) of a predetermined size; • - determining the image defocus of the at least one image portion (S), • - determining the orientation of the contact lens (1) from the image (10) of the contact lens (1) by comparing the determined image defocus with a predetermined threshold (T).