Monocrystalline Silicon MEMS Scanner for Wearable AR
Solution Overview
Problem
Current augmented reality systems require improved display technologies for efficient and compact optical scanners that can minimize size, weight, and energy consumption while maintaining effective scan patterns for wearable devices.
Innovation Solution
The development of optical scanners utilizing a cantilevered beam assembly with torsional flexures and magnetic transducers, which includes a pivoting portion with a cantilevered beam that resonates in a bend mode, allowing for both vertical and horizontal motion to achieve a raster scan pattern, and optionally incorporating piezoelectric actuators for horizontal motion, all formed from a monocrystalline silicon substrate to reduce thickness and eliminate the need for separate waveguides and power routing to the pivoting portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional optical scanner designs are used, then the scanner can perform basic scanning functions, but the size, weight, and thickness increase making it unsuitable for wearable devices
Solution Approach 1:
The patent merges multiple functional components into a single integrated monocrystalline silicon substrate structure. The cantilevered beam assembly, torsional flexures, waveguides, and transducer elements are all formed from the same substrate material, eliminating the need for separate assemblies and reducing overall scanner volume and thickness to enable wearable integration.
Solution Approach 2:
The patent employs ultra-thin monocrystalline silicon substrate with thickness of about 100 microns, forming a thin-film structure that maintains mechanical flexibility while providing sufficient structural integrity for the scanning mechanism. This thin-film approach dramatically reduces the scanner's thickness for wearable applications.
2Manufacturing precision
If multiple separate components are used for the scanner assembly, then each component can be optimized independently, but the number of assembly steps and manufacturing complexity increase
Solution Approach 1:
The patent combines multiple independently optimizable functions into a single monocrystalline silicon substrate using semiconductor manufacturing processes. The cantilevered beam, torsional flexures, waveguides, and transducer elements are all formed through integrated processing steps that allow independent optimization of each feature while maintaining unified manufacturing.
Solution Approach 2:
The monocrystalline silicon substrate serves multiple functions simultaneously: it provides the structural backbone for the cantilevered beam assembly, forms the torsional flexures for rotation, creates the waveguides for light delivery, and supports the transducer elements. This multi-functionality eliminates the need for separate components and assembly steps.
3Use of energy by moving object
If power routing is provided to the pivoting portion, then the transducer can be powered, but additional wiring and assembly complexity are required
Solution Approach 1:
The patent employs a magnetic transducer system where permanent magnets are positioned on the pivoting portion and interact with electromagnetic coils on the stationary portion. The permanent magnets provide their own magnetic field without requiring power, eliminating the need for power routing to the pivoting portion while still enabling actuation through the interaction with the stationary electromagnetic coils.
Solution Approach 2:
The patent extracts the power consumption requirement from the pivoting portion by using permanent magnets instead of electromagnets on the moving part. The magnetic field generation is separated into the stationary portion where power can be efficiently supplied, leaving the pivoting portion passive and free of wiring requirements.
4Illumination intensity
If separate waveguide structures are used, then light delivery can be optimized, but additional assembly steps and component count increase
Solution Approach 1:
The patent integrates the waveguide structures directly into the monocrystalline silicon substrate, forming light delivery channels within the same material as the mechanical scanning components. This merging of optical and mechanical functions into a single substrate eliminates separate waveguide assemblies and reduces the number of assembly steps.
Solution Approach 2:
The patent uses the monocrystalline silicon substrate as a composite structure that simultaneously provides mechanical support, rotational flexibility through torsional flexures, and optical waveguide functionality. The unified material structure allows optimized light delivery while eliminating the need for separate waveguide components.
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 enables the creation of miniaturized, energy-efficient optical scanners that can be integrated into wearable devices, reducing the overall thickness to about 100 microns and allowing for efficient light delivery and scan patterns without the need for additional assembly steps or power routing to the pivoting portion, enhancing the performance and usability of augmented reality systems.
Implementation Method 1
a first magnetic element disposed on the pivoting portion and a second magnetic element disposed on the stationary portion, the first and second magnetic elements being configured to generate magnetic fields that interact to rotate the pivoting portion relative to the stationary portion
Implementation Method 2
a pivoting portion having a cantilevered beam dimensioned to resonate in a bend mode in a plane at a first frequency
Implementation Method 3
at least one torsional flexure coupling the pivoting portion to the stationary portion, the at least one torsional flexure being configured to allow the plane within which the cantilevered beam is positioned to rotate about an axis defined by the at least one torsional flexure
Data Source
AI summary
An optical scanner is described and includes an optical beam assembly and a transducer. The optical beam assembly includes a pivoting portion having a cantilevered beam; a stationary portion; a first torsional flexure coupling a first side of the pivoting portion to the stationary portion; and a second torsional flexure coupling a second side of the pivoting portion to the stationary portion. The transducer includes a first magnetic element disposed on the pivoting portion and a second magnetic element disposed on the stationary portion. The first and second magnetic elements are configured to generate magnetic fields that interact to rotate the pivoting portion relative to the stationary portion about an axis defined by the first and second torsional flexures.