Meander Piezo Actuator Mirror Mass Imbalance
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Solution Overview
Problem
Prior art optical deflectors with meander-type piezoelectric actuators suffer from deviation of the rocking axis of the mirror from its symmetrical axis due to the folding of piezoelectric cantilevers, leading to inaccurate light scanning.
Innovation Solution
The optical deflector design includes a mirror structure divided into two portions along its symmetrical axis, with a mass imbalance by making the second half portion heavier than the first, to prevent deviation of the rocking axis from the symmetrical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If meander-type piezoelectric actuators with rigid folded portions are used to increase drive force and flexing angle, then the mirror can be driven at non-resonant frequencies, but the rocking axis of the mirror deviates from the symmetrical axis toward the folded portion, causing inaccurate light scanning
Solution Approach 1:
The invention applies asymmetry by creating an ill-balanced mirror structure where the mass distribution is intentionally made asymmetric relative to the symmetrical axis. Specifically, the mirror structure includes a first half portion and a second half portion along the symmetrical axis, where the second half portion has a larger mass than the first half portion. This asymmetric mass distribution generates a counterbalancing moment that offsets the axis deviation caused by the piezoelectric actuators, allowing the rocking axis to remain coincident with the symmetrical axis while maintaining the benefits of increased drive force from the meander-type actuators
2Force
If the rocking axis deviates from the symmetrical axis, then the drive force is sufficient, but the irradiated area shifts or changes size, leading to image shifting or enlargement
Solution Approach 1:
The invention implements the counterweight principle by designing the mirror structure with an ill-balanced mass distribution. The second half portion of the mirror structure has a larger mass than the first half portion, creating a counterbalancing effect that compensates for the asymmetric forces generated by the piezoelectric actuators during rocking motion. This counterweight mechanism ensures that the rocking axis remains aligned with the symmetrical axis, preventing image shifting or enlargement while maintaining sufficient drive force for operation at non-resonant frequencies
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 mass imbalance effectively suppresses the deviation of the rocking axis, ensuring accurate light scanning and image generation without shifting or enlarging the irradiated area.
Implementation Method 1
at least one meander-type piezoelectric actuator coupled between the mirror structure and the outer frame and having a plurality of piezoelectric cantilevers
Data Source
AI summary
An optical deflector includes a mirror structure having a symmetrical axis on a plane of the mirror structure, an outer frame surrounding the mirror structure, and at least one meander-type piezoelectric actuator coupled between the mirror structure and the outer frame and having a plurality of piezoelectric cantilevers in parallel with the symmetrical axis folded at folded portions. The mirror structure is divided into a first half portion and a second half portion along the symmetrical axis. The first half portion is close to a closest one of the folded portions, and the second half portion is far from the closest one of the folded portions. A mass of the second half portion is larger than a mass of the first half portion.