Mirror Unit Protrusion Structure for Thin Window Scanning Accuracy
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Solution Overview
Problem
Existing mirror units face challenges in achieving highly accurate light scanning due to potential warping of the window member caused by thermal deformation, which affects the refractive angle and accuracy of light scanning, especially when the window member is thin and exposed to external forces.
Innovation Solution
A mirror unit design featuring a protrusion on the package top surface extending along the light incident opening, with a window member positioned inward of the protrusion, where the protrusion's end surface is further out than the window member, and its thickness is smaller than its height, reducing thermal deformation and stress transfer to the window member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the window member is formed to be thin to reduce refraction, then light scanning accuracy is improved, but the window member becomes more susceptible to warping when the package is thermally deformed
Solution Approach 1:
The protrusion acts as an intermediary protective structure between the package body and the window member. It provides mechanical support and isolation, preventing direct thermal stress transmission to the thin window member while allowing the window to maintain its thin profile for reduced refraction
Solution Approach 2:
The protrusion is designed with a thickness smaller than its height, creating a compliant buffer zone that absorbs thermal deformation stresses before they reach the window member. This beforehand cushioning prevents warping while allowing the window to remain thin
2Device complexity
If the window member is placed directly on the package, then the structure is simple, but the window member is vulnerable to external forces and damage
Solution Approach 1:
The package structure is segmented into distinct functional zones: the main body portion, the protrusion as an intermediate protective layer, and the window member as the optical interface. This segmentation provides both protection and simplicity
3Strength
If the protrusion thickness is increased to protect the window member, then external force protection is improved, but thermal deformation increases causing more stress on the window member
Solution Approach 1:
The protrusion dimensions are optimized with a specific parameter relationship where thickness is smaller than height. This parameter change creates the ideal balance between mechanical protection and thermal deformation resistance, allowing the protrusion to be compliant rather than rigid
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 ensures reliable protection of the window member while maintaining accurate light scanning by minimizing thermal deformation and refraction effects, allowing for precise alignment and reduced warp deformation.
Implementation Method 1
a refractive angle of light in the window member changes
Implementation Method 2
when the package thermally contracts or thermally expands (which may hereinafter be collectively stated as being thermally deformed) due to change of an environmental temperature
Data Source
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AI summary
A mirror unit includes a light scanning device and a package. The package has a main body portion provided with a light incident opening that opens on one side in a predetermined direction and holding the light scanning device, a protrusion provided on a top surface of the main body portion so as to extend along an edge of the light incident opening, and a flat plate-shaped window member disposed on the top surface on an inward side of the protrusion and covering the light incident opening. An end surface of the protrusion on the one side is positioned more to the one side than the window member. A thickness of the protrusion is smaller than a height of the protrusion from the top surface. When viewed in any direction perpendicular to the predetermined direction, a length of a part covered by the protrusion in the window member is longer than a length of a part exposed from the protrusion in the window member.