Optical Scanner Case Surface Roughness for ESD Protection
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Solution Overview
Problem
Optical scanning devices are prone to electrostatic discharge (ESD) damage during assembly and transportation, leading to potential damage to electronic components like laser drivers and motor drivers, especially when resin cases and lids are not properly de-electrified, and existing countermeasures are inefficient.
Innovation Solution
The optical scanning device incorporates a resin case and lid with strategically roughened surfaces to reduce electrostatic charging, using techniques like wrinkling, etching, or sandblasting to create regions with specific surface roughness (6 μm to 40 μm) around electronic components and display areas, which helps in minimizing contact and charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner surface of the case is roughened to prevent laser beam reflection, then optical performance is improved, but surface area for contact increases leading to higher electrostatic charge accumulation
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions of the case. The inner surface is roughened to prevent laser beam reflection, while the outer surface is kept smooth to minimize electrostatic charge accumulation from contact. This local differentiation of surface properties resolves the contradiction between optical performance and electrostatic protection.
2Object-affected harmful factors
If de-electrification operation is performed with an ionizer to reduce surface potential, then electrostatic charge is reduced, but time consumption increases and interior potential remains unaffected
Solution Approach 1:
The patent incorporates electrostatic prevention features directly into the case structure during manufacturing, rather than requiring post-manufacturing de-electrification operations. The smooth outer surface is designed to minimize charge accumulation from the start, eliminating the need for time-consuming ionizer operations and providing protection throughout the device lifecycle.
3Manufacturing precision
If resin molding is performed with high precision requirements, then component precision is improved, but surface roughness must be reduced affecting flowability and releasability
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions of the resin case. The outer surface is kept smooth to ensure good flowability and releasability during molding, while the inner surface is roughened to prevent laser beam reflection. This local differentiation allows high precision component manufacturing without compromising the molding process.
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 roughened surfaces effectively reduce the risk of electrostatic discharge damage to electronic components by minimizing contact electrification and static charge accumulation, enhancing the protection of sensitive components during handling and assembly.
Implementation Method 1
at least a partial region of an outer planar surface of at least one of the case and the lid is roughened... effectively reduce the risk of electrostatic discharge damage to electronic components by minimizing contact electrification and static charge accumulation
Data Source
AI summary
The present invention roughens at least a partial region of an outer planar surface of at least one of an optical case and a lid of a laser scanner; thus, electrification of the optical case to be caused by friction with another member or a person is reduced, and damage to an electronic component is prevented.