Optical Deflection Device Mirror Flatness Control
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Solution Overview
Problem
Conventional optical deflection devices face issues with the deterioration of mirror flatness due to deformation of detection-use piezoelectric elements, which affects the accuracy of deflection angle detection.
Innovation Solution
An optical deflection device is designed with a mirror supported by a torsion bar and cantilevers, featuring a first and second piezoelectric element on the beam, where a control unit measures operation time and corrects detection voltage fluctuations to maintain mirror deflection accuracy without compromising mirror flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detection-use piezoelectric element is continuously connected to the mirror via a torsion bar to detect deflection angle, then deflection angle detection is enabled, but flatness of the reflection face of the mirror deteriorates due to deformation of the piezoelectric element
Solution Approach 1:
The support structure is divided into separate functional segments: drive-use piezoelectric elements for actuation, detection-use piezoelectric elements for sensing, and a torsion bar for mechanical coupling. This segmentation allows each component to perform its specific function without interfering with the mirror's flatness, as the detection element is electrically connected through the torsion bar rather than being directly attached to the mirror surface.
Solution Approach 2:
The torsion bar serves as an intermediary element that mechanically connects the detection-use piezoelectric element to the mirror while allowing electrical signals to be transmitted without direct physical contact between the piezoelectric element and the mirror surface. This intermediary structure enables deflection detection while preserving mirror flatness.
2Measurement precision
If piezoelectric elements are connected to the mirror support structure to enable deflection detection, then detection functionality is achieved, but stress is applied to the mirror support structure
Solution Approach 1:
The support structure is segmented into distinct functional zones: the torsion bar handles mechanical torque transmission, while the piezoelectric elements are positioned on the beam structure away from the critical torsion bar region. This segmentation minimizes stress concentration on the mirror support structure while maintaining detection capability.
Solution Approach 2:
The torsion bar acts as a stress-isolating intermediary that transmits mechanical deformation from the mirror to the detection circuit without requiring the piezoelectric element to be directly attached to the mirror support structure. This reduces the stress burden on the overall support 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
The solution enables precise detection of mirror deflection angles without deteriorating the mirror's flatness, ensuring stable and accurate optical scanning in applications like laser printers and projectors.
Implementation Method 1
voltage is applied to the drive-use piezoelectric element to deform the drive-use piezoelectric element to deflect or oscillate the mirror via the torsion bar
Implementation Method 2
the detection-use piezoelectric element deforms due to deflection or oscillation of the mirror, and then generates voltage corresponding to a deflection angle of the mirror
Data Source
AI summary
An optical deflection device includes a mirror (13a) having a reflection face for deflecting light that enters the reflection face; and a support member (13b, 13c, 13d, 13e, 13f, 13g, 13h, 13i, 13j) to support the mirror (13a), the support member (13b-13j) including a torsion bar (13b, 13c) having one end being continuously connected to the mirror; a beam (13d, 13e) being continuously connected to another end of the torsion bar (13b, 13c); and a plurality of piezoelectric elements (13f, 13g, 13h, 13i) disposed on the beam (13d, 13e) including a first piezoelectric element (13f, 13g) and a second piezoelectric element (13h, 13i).