Piezoelectric Sensor Tilted Side Surface Stress Distribution
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Solution Overview
Problem
In optical scanning devices, the close proximity between the driven portion and the piezoelectric sensor leads to stress concentration on the piezoelectric thin film, increasing the risk of sensor failure.
Innovation Solution
The optical scanning device incorporates a piezoelectric sensor with a tilted side surface, where the tilt angle of the piezoelectric thin film is greater than 0° and less than or equal to 50°, to distribute stress effectively and prevent concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the driven portion and the piezoelectric sensor are arranged close to each other, then the output S/N ratio is improved, but stress concentration on the piezoelectric thin film increases and the sensor reliability deteriorates
Solution Approach 1:
The side surface of the piezoelectric thin film is made into a tilted surface with a specific tilt angle (greater than 0° and less than or equal to 50°) to create local structural differentiation. This local quality change allows the sensor to maintain close proximity to the driven portion for high S/N ratio while the tilted surface specifically addresses stress concentration at the side surface, thereby improving reliability without sacrificing measurement precision
2Reliability
If the side surface of the piezoelectric thin film is made into a tilted surface, then stress concentration is relaxed and durability is improved, but manufacturing complexity increases
Solution Approach 1:
The tilt angle of the side surface is optimized to be greater than 0° and less than or equal to 50°. This parameter range balances the competing requirements: angles greater than 0° provide stress relief and improve durability, while angles less than or equal to 50° keep the manufacturing process feasible and not excessively complex
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 relaxes stress concentration on the piezoelectric sensor, enhancing its durability and reliability even when the distance between the driven portion and the sensor is close, while maintaining the necessary proximity for high S/N ratio output.
Implementation Method 1
a piezoelectric sensor (192) formed on the connection beams (140A and 140B) and configured to detect a displacement of the connection beams (140A and 140B) caused by a swing of the mirror (110)
Data Source
AI summary
An optical scanning device includes: a pair of twist beams arranged on both sides of a mirror along a predetermined axis and configured to swing the mirror around the axis; a pair of connection beams connected to the respective twist beams; a piezoelectric sensor formed on the connection beams and configured to detect a displacement of the connection beams caused by a swing of the mirror around the axis; wherein the piezoelectric sensor includes a lower electrode; a piezoelectric thin film stacked on the lower electrode; and an upper electrode stacked on or above the piezoelectric thin film, wherein a bottom surface and a side surface of the piezoelectric thin film form a tilt angle θ, and wherein the tilt angle is greater than 0° and less than or equal to 50°.