Pivotable PCB Section With Flexible Web for Smoke Detection

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Solution Overview

Problem

Existing optical smoke detectors face manufacturing inefficiencies and mechanical sensitivity due to weakened circuit board sections, which are prone to damage from impact or vibration, and require significant processing effort for tapering.

Innovation Solution

The design features a continuous recess on the printed circuit board with a flexible web that can pivot between 30° to 90°, allowing for reversible deformation without material damage, reducing mechanical sensitivity and eliminating the need for removal processing, and enabling mass production with low additional processing effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a weakened printed circuit board section is used for pivoting, then the optical detection function can be achieved, but the mechanical robustness deteriorates and the section becomes prone to breaking

Engineering Contradiction:

Improvepivoting capabilityVSAvoidmechanical robustness

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies this principle by creating a flexible web structure within the printed circuit board that allows controlled pivoting motion. The web is designed with specific dimensional proportions (web length to web width ratio between 2:1 and 10:1) to provide sufficient flexibility for pivoting while maintaining structural integrity and resistance to breaking under impact or vibration loads.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent applies this principle by carefully controlling the geometric parameters of the web structure, specifically the web length and web width dimensions. By optimizing the ratio between web length and web width, the design achieves the optimal balance between flexibility (enabling pivoting) and strength (preventing breakage), transforming the mechanical properties of the circuit board section.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a weakened printed circuit board section is created by removal process, then the pivoting function is enabled, but the manufacturing effort and complexity increase

Engineering Contradiction:

Improvepivoting capabilityVSAvoidmanufacturing effort

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies this principle by pre-defining the web geometry during the standard printed circuit board manufacturing process. The web structure with optimized dimensions is built into the board design from the beginning, allowing the pivoting function to be achieved without requiring subsequent weakening or removal processes. This eliminates additional manufacturing steps and reduces overall manufacturing effort.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If the web length is increased to improve flexibility, then the pivoting capability is enhanced, but the mechanical strength of the web decreases

Engineering Contradiction:

Improvepivoting flexibilityVSAvoidweb strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies this principle by optimizing not just the web length but the critical ratio between web length and web width. By maintaining this ratio between 2:1 and 10:1, the design achieves the optimal balance where the web is flexible enough to allow repeated pivoting motions while remaining strong enough to resist breaking under impact or vibration, preventing both excessive rigidity and excessive weakness.

Inventive Principle:

Principle #35Parameter changes

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 enhances the mechanical robustness and manufacturing efficiency of optical smoke detectors, allowing for repeated pivoting without structural damage and simplifying the production process by eliminating the need for tapering, while maintaining compliance with mechanical standards.

Implementation Method 1

the respective web has a (minimum) web length dimensioned in such a way that a bending and/or torsional moment introduced into the respective web in the pivoted position deforms the respective web in a flexible, in particular reversibly flexible, manner

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3454312B1Optical smoke alarm with a pivotable conductor plate section with a light transmitter and/or receiver arranged on same

Publication Date: 2019.08.07 SIEMENS SCHWEIZ AG

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AI summary

The invention relates to an optical smoke detector comprising a printed circuit board (2) with a uniform thickness (D), a light transmitter (4), and a light receiver (5). The light transmitter and the light receiver are each arranged on a section (3) of the printed circuit board. Each section of the printed circuit board can be pivoted from a flat position in a common plane with the printed circuit board to a pivoting position intended for optical smoke detection and then fixed there. Characteristically, the pivoting position has an angle (σ) in a range of 30° to 90°. At least one of the two printed circuit board sections is formed by at least one continuous recess (S) in the printed circuit board, except for at least one remaining web (ST).The respective web has a web length (L) dimensioned such that a bending and/or torsional moment introduced into the respective web in the pivot position deforms the respective web (only) elastically in bending.