Optical Scanning Device Torsion Bar Spring Constant Distribution
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Solution Overview
Problem
Existing optical scanning devices face challenges in miniaturization due to the need for a large mirror size to achieve sufficient image resolution, which increases the size of the device and limits the scan angle, and metal torsion bars suffer from fatigue, while brittle materials have limited torsion angles, and there are issues with light absorption and inefficient vibration transmission.
Innovation Solution
The optical scanning device uses a substrate with a mirror portion supported by torsion bar portions, where the mirror is extended to surround the torsion bars or notches are cut to increase mirror size without changing overall length, distributes spring constant along the torsion bars to reduce length, uses metal or plastically deformable materials for torsion bars to impart deflection angles, and forms a single piezoelectric film to enhance vibration efficiency and reduce unnecessary vibration modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mirror size is increased to achieve sufficient image resolution, then the image resolution is improved, but the device size increases and the scan angle is limited
Solution Approach 1:
The mirror is designed to surround the torsion bars, with the torsion bars positioned inside the mirror structure. This nesting arrangement allows the mirror to achieve a larger effective scanning area without proportionally increasing the overall device footprint, as the torsion bars are housed within the mirror's structural space rather than occupying additional external space.
Solution Approach 2:
The torsion bars are extended in the axial direction of the mirror, utilizing the depth dimension rather than only the lateral dimensions. By distributing the spring constant along the axial length of the torsion bars, the design achieves increased mirror size and scanning capability without necessarily increasing the device's planar footprint.
2Reliability
If metal torsion bars are used, then the device durability is improved, but the torsion bars suffer from fatigue
Solution Approach 1:
The spring constant is distributed non-uniformly along the axial direction of the torsion bars, with different sections having different stiffness characteristics. This local variation in mechanical properties allows certain sections to absorb and dissipate stress more effectively, reducing fatigue accumulation in critical areas while maintaining overall structural integrity and durability.
3Volume of moving object
If brittle materials are used for torsion bars, then the device size is reduced, but the torsion angles are limited
Solution Approach 1:
The spring constant distribution along the torsion bars is optimized to achieve the desired balance between device size and torsion angle. By carefully controlling the stiffness parameters in different axial sections, the design enables sufficient torsion angle range for effective scanning while maintaining a compact device footprint suitable for portable applications.
4Productivity
If a single piezoelectric film is used, then the vibration efficiency is improved and unnecessary vibration modes are reduced, but the manufacturing complexity increases
Solution Approach 1:
Multiple piezoelectric elements are integrated into a single continuous piezoelectric film that spans across the substrate. This merged structure eliminates the need for separate elements and their individual connections, reducing manufacturing complexity while maintaining the ability to generate controlled vibrations. The single film approach also reduces unnecessary vibration modes by providing a more uniform actuation surface.
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 design allows for a smaller device size with efficient torsional vibration, increased mirror size, improved scan angles, and enhanced light transmission, achieving high-accuracy optical beam scanning with reduced size and cost.
Implementation Method 1
a piezoelectric film 15 which vibrates in piezoelectric oscillation when voltage is applied from a power source 16
Implementation Method 2
torsional vibration is induced in the torsional deformation component 105, and the two drive sources are driven at the resonance frequency of the torsional deformation component 105
Implementation Method 3
irradiates light which is emitted from a light source 100 and reflected by a mirror portion 101 onto a detection object 102
Data Source
AI summary
An optical scanning device of the invention includes: a substrate; torsion bar portion which is connected to the substrate; a mirror portion which is supported by the torsion bar portion; a drive source which causes the substrate to oscillate; and a light source which projects light onto the mirror portion, where the mirror portion resonates and vibrates in accordance with a vibration imparted to the substrate by the drive source, and the direction of reflection light from the light projected onto the mirror portion from the light source changes in accordance with the vibration of the mirror portion, and a spring constant in a longitudinal direction of the torsion bar portion supporting the mirror portion is distributed along the longitudinal direction of the torsion bar portion.