Optical Scanning Device Deformable Frame Structure Vibration Resistance
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Solution Overview
Problem
The optical scanning device in laser projectors, which uses a fine beam structure for rotating a scanning mirror, is prone to limitations in rotation range due to external forces like vibration or shock and temperature changes, and has high manufacturing costs associated with MEMS technology.
Innovation Solution
The device employs a frame structure with deformable base portions and a supporting shaft to allow the scanning mirror to rotate, reducing the impact of external forces and eliminating the need for MEMS technology by using a machined metal or molded resin frame structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the beam structure size is increased to enhance resistance to vibration or shock, then the resistance to external forces is improved, but the range of rotation of the scanning mirror is further limited
Solution Approach 1:
The frame structure is divided into multiple beams (first beam and second beam) that are disposed parallel to each other, with the scanning mirror positioned between them. This segmentation allows each beam to be optimized independently for both strength and rotation range, resolving the contradiction between enhancing resistance to external forces and maintaining a wide rotation range.
2Volume of moving object
If MEMS technology is used to achieve downsizing of the optical scanning device, then the device size is reduced, but the manufacturing cost increases
Solution Approach 1:
The patent replaces the MEMS (Micro Electro Mechanical System) technology with a conventional mechanical frame structure made of metal or resin. This substitution eliminates the need for expensive semiconductor manufacturing equipment while achieving similar downsizing effects, thus resolving the contradiction between compact device size and high manufacturing cost.
3Reliability
If the beam structure is made more robust to resist external forces, then the reliability is improved, but the range of rotation is limited
Solution Approach 1:
The frame structure employs different thicknesses for different beams: the first beam has a greater thickness than the second beam. This local quality differentiation allows the structure to be more robust where needed (first beam) while maintaining adequate rotation range in other areas (second beam), thus resolving the contradiction between reliability and rotation range.
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 enhances the device's resistance to vibration and temperature changes, enabling stable scanning without the high costs of MEMS technology, while allowing for efficient assembly and reduced power consumption.
Implementation Method 1
a first scanning driving unit configured to cause the scanning mirror to rotate about a first rotation axis by means of deformation of the frame structure
Implementation Method 2
a supporting shaft that supports the rotation holder so that the rotation holder is rotatable about a second rotation axis
Data Source
AI summary
An optical scanning device includes a first scanning driving unit and a second scanning driving unit. The first scanning driving unit includes a scanning mirror and a frame structure supporting the scanning mirror. The first scanning driving unit is configured to cause the scanning mirror to rotate about a first rotation axis by means of deformation of the frame structure. The second scanning driving unit includes a rotation holder supporting the first scanning driving unit and a supporting shaft. The second scanning driving unit is configured to cause the rotation holder to rotate about the second rotation axis. The frame structure includes a pair of beams provided so as to sandwich the scanning mirror in a direction of the first rotation axis, and a pair of base portions provided on sides of respective beams of the pair of beams opposite to the scanning mirror. Each of the pair of base portions has an elongated shape elongated in a direction of the second rotation axis, and is deformable.