Limited-Reflection Sensor Lens Assembly for Dust-Resistant Alignment
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Solution Overview
Problem
Conventional limited reflection type sensors face complications in assembly due to the need for precise alignment of lenses, which complicates the process and increases the risk of dust ingress, especially when integrating the exit and receiving light lenses into the casing.
Innovation Solution
The sensor design incorporates a latching portion on the casing side surface with a snap-fit structure and a guide groove for the side surface covering part, allowing easy and accurate alignment of the lens, while enhancing dust resistance through sealing grooves and projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lens is inserted into the casing with holding and alignment to latching portion, then the lens can be securely mounted, but the assembly process becomes complicated
Solution Approach 1:
The lens mounting structure is segmented into distinct functional elements: the casing with integrated latching portions, the lens with protrusions, and the lid with corresponding latching features. This segmentation allows each component to perform its specific function independently, simplifying the overall assembly process while maintaining secure mounting.
Solution Approach 2:
The latching portions are merged directly into the casing structure, eliminating the need for separate alignment fixtures or additional mounting hardware. The protrusions on the lens are integrated with the lens itself, and the lid's latching portions are combined with the closing operation, reducing assembly steps and complexity.
2Manufacturing precision
If projection and hole are integrally formed on the lens for alignment, then the lens can be aligned with latching portion, but the lens shape becomes complicated and processing difficulty increases
Solution Approach 1:
The alignment protrusions are designed as asymmetric features with specific geometries that provide unique orientation and positioning. The protrusions have different shapes and positions that naturally guide the lens into the correct alignment with the latching portions, ensuring precise positioning without requiring complex symmetric features or additional alignment marks.
Solution Approach 2:
The latching portions and protrusions are pre-formed during lens manufacturing, so that alignment features are already in place before the lens is installed in the casing. This preliminary formation of alignment features eliminates the need for post-manufacturing alignment operations or complex machining steps, simplifying both manufacturing and assembly processes.
3Object-affected harmful factors
If the lid is mounted to cover the casing upper portion, then dust and dirt entry is prevented, but it becomes difficult to check lens assembly and alignment
Solution Approach 1:
The latching portions on the lid are designed to be extractable or removable features that allow the lid to be opened and closed. This extraction capability enables inspection of the lens and its alignment with the casing's latching portions, while still providing dust and dirt protection when the lid is closed. The latching mechanism can be quickly released to allow access for checking lens assembly without requiring disassembly of the entire device.
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 facilitates easy and accurate lens alignment, reduces assembly complexity, and enhances dust resistance by preventing dust ingress, thus simplifying the process and improving sensor performance.
Implementation Method 1
irradiates exit light from a light emitting unit toward an object sensing region through an exit light lens
Implementation Method 2
the light is converted into an electric signal by the light receiving unit, and hence the presence of an object in the sensing region can be sensed by detecting a voltage change occurring in the light receiving unit
Data Source
AI summary
A limited reflection type sensor which irradiates exit light from a light emitting unit toward an object sensing region through an exit light lens and receives, at a light receiving unit, reflected light from an object existing in the object sensing region through a reflected light lens, may include a casing including a latching portion formed on a side surface and a first opening facing the object sensing region, the casing accommodating the light emitting unit and the light receiving unit; and a lens part including a light incident/exit part formed integrally with the exit light lens and the reflected light lens, and a side surface covering part in which an end of the light incident/exit part is extended along the side surface, in which the lens part covers the first opening with the light incident/exit part and the side surface covering part is latched by the latching portion.