Flexure Mounting for Optical Alignment in Intraoral Scanners
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Solution Overview
Problem
In dental and orthodontic procedures, obtaining accurate 3D models of the oral cavity is crucial for designing optimal prosthetics and appliances, but existing methods often result in suboptimal models due to incomplete or undefined data, leading to issues like prosthesis collisions and improper finish line design.
Innovation Solution
A mounting system using flexures that allow for thermal expansion and contraction of optical elements while preventing translational or rotational movement, ensuring precise alignment and stability of optical components on a printed circuit board, even with different coefficients of thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical elements are rigidly mounted on a PCB, then alignment precision is maintained, but thermal stress and component damage occur due to different coefficients of thermal expansion
Solution Approach 1:
The patent employs flexible mounting structures including flexures and compliant mechanisms that allow controlled deformation to accommodate thermal expansion differences between optical elements and the PCB substrate. These flexible elements maintain optical alignment precision while absorbing thermal stress through elastic deformation rather than rigid constraint.
Solution Approach 2:
The patent utilizes materials with specific thermal expansion coefficients and designs mounting structures with controlled stiffness parameters that change with temperature. By selecting materials and structural parameters that match or compensate for thermal expansion differences, the system maintains alignment precision across varying thermal conditions without generating excessive stress.
2Object-affected harmful factors
If flexible mounting structures are used to accommodate thermal expansion, then thermal stress is reduced, but alignment precision deteriorates
Solution Approach 1:
The mounting system is divided into multiple segmented components including flexures, compliant mechanisms, and adjustable mounting elements. Each segment is designed to handle specific aspects of thermal compensation while maintaining overall alignment. The segmented structure allows controlled movement in non-critical directions while preserving precision in critical optical alignment directions.
Solution Approach 2:
The patent employs dynamic mounting structures that can adapt their stiffness and compliance characteristics in response to thermal conditions. The flexible elements are designed to provide appropriate compliance during thermal expansion while maintaining rigid constraints for precise optical alignment during operation, transitioning between different mechanical states based on thermal input.
3Strength
If thermal expansion is fully accommodated, then component stress is minimized, but positional stability of optical elements deteriorates
Solution Approach 1:
The mounting system implements different mechanical properties at different locations and directions. Flexures and compliant mechanisms are designed with anisotropic stiffness characteristics that provide high stability in directions critical for optical alignment while allowing controlled expansion in non-critical directions. This local differentiation of mechanical properties simultaneously achieves stress minimization and positional stability.
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 solution maintains sub-micron accuracy and stability of optical alignment over a wide range of thermal conditions, enabling high-quality 3D data capture and minimizing stress on components, thus improving the design and fit of dental and orthodontic devices.
Implementation Method 1
the first and second flexures being flexible respectively along a first axis and a second axis that are generally parallel to a face of the detector, such that thermal expansion or contraction of the optical element and/or the base bends the flexures
Implementation Method 2
the first and second flexures being rigid respectively perpendicular to the first axis and the second axis, such that the first and second flexures prevent translational or rotational movement of the optical element with respect to the base
Data Source
AI summary
A scanner for scanning a dental site comprises a base, a detector mounted to the base, and an optical element to redirect light reflected off of the dental site towards the detector along a detection axis in a first direction. Two or more flexures couple the optical element to the base, wherein the two or more flexures maintain an alignment of the optical element to the detector with changes in temperature.