Arc-Shaped Aperture Member for Smoke Detector Optical Alignment
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Solution Overview
Problem
Existing smoke detectors using hard materials like iron plates for apertures face challenges in accurately aligning and orienting the aperture member to prevent diffracted light, due to potential burrs from manufacturing processes, which can cause misalignment and increased diffracted light generation.
Innovation Solution
The smoke detector design features an aperture member with a lower surface formed into an arc shape, matched by a corresponding arc-shaped receiving portion on the main body, along with asymmetric side surfaces, allowing easy alignment and orientation to ensure the aperture's center position is on the optical axis and oriented correctly to minimize diffracted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If another hard material such as an iron plate is used as an aperture member to maintain strength when thinned, then the aperture strength is improved, but the alignment precision and orientation accuracy deteriorate due to burrs remaining on the opening edge portion
Solution Approach 1:
The patent applies preliminary action by forming a recess portion in advance on the main body at the position where the aperture member will be mounted. This recess portion is designed with specific dimensional relationships to the light passage opening, enabling automatic centering and alignment of the aperture member during assembly, thereby preventing misalignment caused by burrs without requiring additional alignment operations
Solution Approach 2:
The recess portion acts as an intermediary structure between the main body and the aperture member. It provides a dedicated mounting interface that mediates the alignment relationship, ensuring that the light passage opening of the aperture member is precisely positioned on the optical axis through the geometric constraints of the recess portion
2Object-generated harmful factors
If the aperture is thinned to prevent generation of diffracted light, then the diffracted light generation is reduced, but the aperture strength becomes insufficient
Solution Approach 1:
The patent applies local quality by making the aperture member thin only in the region where light passes through (the light passage opening area), while maintaining sufficient thickness at other regions (such as the mounting portion and edges). This localized thinning reduces diffracted light generation at the critical light passage area while preserving overall structural strength through adequate thickness elsewhere
3Manufacturing precision
If the aperture member is mounted to the main body with manual location of center position, then alignment can be achieved, but the operation complexity and time consumption increase
Solution Approach 1:
The patent applies self-service by designing the recess portion and aperture member with complementary geometric features that enable automatic alignment during assembly. The dimensional relationships between the recess portion and light passage opening ensure that the center position is automatically located on the optical axis without requiring manual intervention or complex alignment procedures
Solution Approach 2:
The recess portion is pre-formed on the main body with specific dimensions and positioning, creating a ready-made mounting interface that guides the aperture member into the correct position during assembly, thereby eliminating the need for manual location operations and reducing assembly complexity
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 mounting of the aperture member, ensuring the center position of the light passage opening is aligned with the optical axis and oriented correctly, thereby reducing diffracted light and improving detection accuracy.
Implementation Method 1
a light receiving section receives scattered light generated in a smoke detecting section when light emitted from a light emitting section is scattered due to particles of the smoke or the like
Data Source
AI summary
An aperture member (15) is configured to be mounted to a receiving portion (22) provided to a main body (2), and includes a lower surface portion (15a) formed into an arc shape. The receiving portion (22) of the main body (2) includes a bottom surface portion (22a) formed into a shape corresponding to the arc shape of the lower surface portion (15a) of the aperture member (15) so as to be brought into contact with the lower surface portion (15a) of the aperture member (15). The aperture member (15) includes a light passage opening (15e) formed so that a center position (15ea) thereof substantially matches with a position of a center of curvature of the arc shape of the lower surface portion (15a).