Fold Lens Optical Arrangement for Compact Barcode Imaging
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Solution Overview
Problem
The miniaturization of barcode imaging engines is hindered by the limited space in mobile products, necessitating a compact optical arrangement that balances functionality and size.
Innovation Solution
The implementation of a compact optical lens arrangement featuring a first lens-subarrangement with rotational symmetry and a second lens-subarrangement including a fold lens that refracts, reflects via total internal reflection, and corrects for field curvature, integrated with a printed circuit board and imaging sensor, allowing for efficient light redirection and focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional optical lens arrangement is used, then the imaging engine can capture images effectively, but the depth and overall size of the imaging engine increases
Solution Approach 1:
The patent introduces a fold lens that redirects the optical path at an angle (e.g., 45 degrees) relative to the optical axis, effectively folding the light path into a different spatial dimension. This allows the optical system to achieve the required focal length and image capture capability while reducing the axial depth of the imaging engine, thereby resolving the contradiction between compact size and effective image capture.
Solution Approach 2:
The fold lens is integrated within the lens sub-arrangements, with the first fold lens positioned between the first and second lens sub-arrangements. This nested configuration allows multiple optical functions (refraction, reflection, field curvature correction) to be combined in a compact package, reducing overall imaging engine volume while maintaining imaging effectiveness.
2Length of moving object
If the optical lens arrangement is compacted, then the depth is reduced, but field curvature errors increase
Solution Approach 1:
The fold lens performs multiple functions simultaneously: it redirects the optical path to reduce depth, focuses light onto the imaging sensor, and corrects field curvature through its specifically designed refractive and reflective surfaces. This multi-functionality allows compacting the optical arrangement while maintaining or even improving optical precision, including field curvature correction.
Solution Approach 2:
The patent employs aspherical surfaces on the fold lens with specifically optimized curvature parameters. By carefully controlling the radii of curvature of the first, second, and third surfaces of the fold lens, the design achieves field curvature correction while maintaining a compact form factor, thus resolving the contradiction between reduced depth and optical precision.
3Manufacturing precision
If more optical components are added to correct field curvature, then optical precision improves, but device complexity increases
Solution Approach 1:
The patent combines field curvature correction functionality directly into the fold lens by designing its first, second, and third surfaces with specific curvatures. Instead of adding separate correction lenses or components, the field curvature correction is merged into the existing fold lens structure, thereby improving optical precision without increasing device complexity.
Solution Approach 2:
The fold lens serves as a multi-functional component that simultaneously performs light redirection (to reduce depth), focusing, and field curvature correction. This consolidation of multiple optical functions into a single component avoids increasing device complexity while achieving the desired optical precision and field curvature correction.
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 configuration achieves a compact imaging engine design that maintains a short depth and corrects for field curvature, enabling effective image capture while increasing PCB area for additional electronic components, thus addressing the size constraints in mobile barcode readers.
Implementation Method 1
a first side configured to refract light incoming along the optical axis into the fold lens along a first path
Implementation Method 2
a second side configured to reflect the light via total internal reflection (TIR) and redirect the light along a second path
Implementation Method 3
a third side positioned within the second path, the third side configured to refract the light directed along the second path out of the fold lens and direct the light toward the imaging sensor
Implementation Method 4
at least one of the first side of the fold lens, the second side of the fold lens, and the third side of the fold lens is configured to correct for field curvature
Data Source
AI summary
At least some embodiments of the present invention generally relate to the field of optics, and more specifically, to compact optical arrangements for use in imaging engines likes the ones used in handheld barcode readers. In an embodiment, an imaging engine having a field of view (FOV) includes an imaging sensor and an optical lens configured to (i) fold the FOV once between the imaging sensor and an exit window of the imaging engine and/or the window of a barcode reader within which the imaging engine may be implemented, and (ii) correct for field curvature.