Optical Element Joints for High-Frequency Mirror Rotation
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Solution Overview
Problem
Conventional optical reflecting devices face challenges in achieving high-frequency drive with large rotation angles while maintaining mechanical strength, leading to increased size and decreased scan rates due to stress concentration on torsion bars.
Innovation Solution
The optical reflecting device incorporates a configuration with wider joints than vibration parts, distributing stress and increasing mechanical strength, allowing for high-frequency drive with large rotation angles without enlarging the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the torsion bar is extended to reduce stress concentration, then the mechanical strength is improved, but the device size increases and scan rate decreases
Solution Approach 1:
The patent divides the joint structure into multiple segments: a torsion bar and multiple torsion springs arranged in series. This segmentation allows the stress to be distributed across multiple elastic elements rather than concentrated in a single long torsion bar, thereby maintaining mechanical strength without increasing the overall device size or reducing scan rate.
Solution Approach 2:
The patent employs a nested configuration where multiple torsion springs are arranged within the joint structure alongside the torsion bar. This nesting allows the elastic elements to be compactly integrated, providing the necessary mechanical strength and stress distribution without extending the device dimensions, thus preserving high scan rates.
2Ease of operation
If a piezoelectric actuator is used to rotate the mirror, then the device achieves precise control, but stress concentration occurs on the torsion bar limiting high-frequency drive capability
Solution Approach 1:
The patent combines piezoelectric actuators with a composite joint structure consisting of torsion bars and multiple torsion springs. This composite design allows the piezoelectric actuator to provide precise control while the distributed spring system absorbs and distributes the mechanical stress, enabling high-frequency operation without compromising reliability or control precision.
3Strength
If the joint beam width is increased to reduce stress, then the mechanical strength is improved, but the device size increases
Solution Approach 1:
Instead of increasing the beam width of a single joint, the patent segments the joint into multiple narrower torsion springs arranged in series. This segmentation achieves the stress reduction effect of a wider beam while maintaining a compact overall joint width, thereby improving mechanical strength without increasing device size.
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 enables increased resonance frequency and mechanical deflection angles, maintaining mechanical strength and preventing stress-induced failures, while avoiding the trade-off between size and scan rate.
Implementation Method 1
piezoelectric layers 10 for rotating mirror part 9... When piezoelectric layers 10 are energized, they expand or contract. Due to this expansion or contraction, vibrating beams 4 are twisted to rotate mirror part 9.
Data Source
AI summary
An optical reflecting device includes a mirror part, a pair of joints, a pair of vibration parts, a plurality of driving parts, and a fixed part. Each of the joints has a first end connected to respective one the facing positions to each other on the mirror part and a second end opposite to the first end, and extends along a first axis. Each of the vibration parts has a central portion connected to the second end of respective one of the joints. A plurality of driving parts is disposed in each of the pair of vibration parts, and rotates the mirror part. Both ends of each of the pair of vibration parts are connected to the fixed part. The beam width defined as the length of each of the joints in a direction orthogonal to the first axis is greater than the beam width of each of the pair of vibration parts.