Optical Scanning Device with Piezoelectric Substrate Shape Control
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Solution Overview
Problem
Optical scanners with micro mirrors supported by torsion bars face challenges in maintaining consistent resonance frequency and scan angle due to temperature changes and manufacturing irregularities, leading to instability and increased costs for adjustments.
Innovation Solution
The optical scanning device incorporates a substrate shape control mechanism, including a stress-applying piezoelectric film or shape memory alloy, to adjust the substrate's spring constant and shape, ensuring constant resonance frequency and stable scan angle across varying temperatures and production irregularities, by forming a piezoelectric film on the substrate and using a magnetic material or bimetal structure for deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a micro mirror supported by torsion bars is used for optical scanning, then the scanning function is achieved, but the resonance frequency and scan angle become unstable due to temperature changes and manufacturing irregularities
Solution Approach 1:
The patent applies parameter changes by using a piezoelectric element to dynamically adjust the spring constant of the torsion bar through voltage control. This allows real-time compensation for temperature-induced changes and manufacturing variations, maintaining stable resonance frequency and scan angle despite external conditions
Solution Approach 2:
The patent implements feedback control by detecting the actual resonance frequency and scan angle, then using this information to adjust the piezoelectric element's voltage output. This closed-loop system continuously corrects deviations caused by temperature changes and manufacturing irregularities, ensuring reliable scanning performance
2Reliability
If adjustment mechanisms are added to compensate for temperature and manufacturing variations, then stability improves, but device complexity increases
Solution Approach 1:
The patent merges the compensation function directly into the existing torsion bar structure by integrating a piezoelectric element within the torsion bar itself. This unified design eliminates the need for separate adjustment mechanisms, reducing overall device complexity while maintaining scan angle stability
Solution Approach 2:
The piezoelectric element enables the torsion bar to self-adjust its spring constant in response to detected variations, performing the compensation function autonomously without requiring external mechanical adjustment mechanisms. This self-service approach simplifies the overall device structure
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 approach allows for efficient generation of torsional vibration in the mirror portion, achieving a stable scan angle over a wider temperature range and reducing scan jitter, thereby enhancing the accuracy and reliability of optical beam scanning.
Implementation Method 1
a piezoelectric film 15 which vibrates in piezoelectric oscillation
Implementation Method 2
using a magnetic material or bimetal structure for deformation
Implementation Method 3
stress-applying piezoelectric film or shape memory alloy
Implementation Method 4
a torsional deformation component 105 which extends from a center portion of the linking component 104
Implementation Method 5
the two drive sources are driven at the resonance frequency of the torsional deformation component 105
Data Source
AI summary
An optical scanning device of the invention includes: a substrate; a 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, a 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, the drive source is provided on a portion of the substrate at a distance from a connected portion where the substrate is connected to the torsion bar portion, and a substrate shape control device which controls the shape of the substrate itself is provided on the substrate.