Back-Side Shielding Device for Light Receiver Electromagnetic Compatibility
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Solution Overview
Problem
Smoke alarms with sensitive light receivers face challenges in achieving high electromagnetic compatibility due to insufficient shielding against electromagnetic interference radiation, leading to potential false alarms and measurement signal corruption.
Innovation Solution
A light receiver device with a shielding device mounted on the back side of a substrate, featuring a metal strip that penetrates the substrate and is fixed in self-retaining fashion, providing comprehensive shielding against electromagnetic interference radiation, and an assembly method that simplifies the mounting process by using a push-in operation or bending to secure the shielding device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal shielding unit is mounted on the front side of the printed circuit board, then electromagnetic compatibility is improved, but shielding against interference radiation impinging from the back side is insufficient
Solution Approach 1:
The shielding device is moved from the conventional front-side mounting to the back side of the substrate, adding a new dimensional approach to shielding. The shielding device extends in multiple directions (laterally, longitudinally, and vertically) from the back side, creating a three-dimensional shielding structure that effectively blocks electromagnetic interference radiation from all directions, particularly from the back side where previous solutions were insufficient.
2Reliability
If a shielding device extends laterally and longitudinally from the back side, then shielding effectiveness is improved, but assembly complexity increases
Solution Approach 1:
Multiple shielding functions are merged into a single integrated shielding device. The shielding device simultaneously provides lateral shielding, longitudinal shielding, and vertical shielding in one component, eliminating the need for multiple separate shielding elements. This integration simplifies the assembly process while maintaining comprehensive shielding effectiveness.
Solution Approach 2:
The shielding device features self-retaining fixation through its vertical extension that engages with the substrate structure. The device's own geometry provides its own mounting mechanism, reducing the need for additional fasteners or complex assembly steps. The shielding device essentially mounts itself when positioned correctly on the back side of the substrate.
3Reliability
If the shielding device is fixed with additional fastening elements, then fixation reliability is improved, but manufacturing cost and assembly time increase
Solution Approach 1:
The shielding device incorporates self-retaining fixation features where its vertical extension and overall geometry enable it to secure itself to the substrate without external fasteners. The device's structure is designed to engage with corresponding features on the substrate, creating a reliable mechanical connection that simplifies manufacturing and assembly while maintaining high fixation reliability.
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 significantly enhances the electromagnetic compatibility of the light receiver device, reducing the likelihood of false alarms and ensuring accurate signal output by effectively shielding against electromagnetic interference, while maintaining a cost-effective and simple assembly process.
Implementation Method 1
a shielding device which is present on at least a back side of the substrate opposite the front side and which is designed such that it at least partially shields against electromagnetic interference radiation which impinges on the light receiver through the substrate
Data Source
AI summary
A light receiver device, which is particularly suited for a smoke detector, has a flat substrate, a light receiver mounted on a front side of the substrate, and a shielding device present on at least a back side of the substrate opposite the front side. The shielding device is configured to at least partially shield against electromagnetic interference radiation impinging on the light receiver through the substrate. False alarms are thereby reduced, while the sensitivity of the light receiver is simultaneously increased. The shielding device is formed with a metal strip inserted through the substrate from the front side to the back side, and bent over a recess on the back side provided therefor, so that the light receiver is protected against interference radiation even on the back side. There is also provided an assembly method for producing a light receiver device.