Tamper-Evident Slide Fastener Security Device with Frangible Weakness
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Solution Overview
Problem
Prior tamper-evident security devices for slide fasteners can be easily removed from containers without breaking the seal, allowing unauthorized access and tampering, as they are rigidly attached and lack sufficient 'play' between the device and the container.
Innovation Solution
A security device with a lower part attached to the container, an upper part that retains a frangible seal and attaching means, and an area of weakness that fractures if the device is prised from the container, allowing for 'play' in attachment and ensuring tampering is evident through visible fracture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the security device is rigidly attached to the container, then the device is securely fixed and cannot be easily removed, but the device cannot have 'play' and can be easily pried off by levering the housing
Solution Approach 1:
The security device is divided into two functional parts: a rigid lower part for secure attachment to the container, and an upper part with a frangible seal for tamper indication. The area of weakness is positioned between these parts, allowing the structure to segment during tampering attempts.
Solution Approach 2:
The patent introduces an area of weakness with specific structural parameters (reduced thickness, geometric features) that change the mechanical properties of the housing. This creates a controlled fracture point that transforms the rigid structure into one that can yield predictably under prising forces, preventing clean removal while maintaining secure attachment.
2Stability of the object's composition
If the housing is made as a single rigid piece, then the structure is strong and stable, but it cannot provide an area of weakness for tamper indication
Solution Approach 1:
The housing has non-uniform structural properties: most of the housing maintains high strength and rigidity for stability, while a specific localized area contains a weakness with reduced structural integrity. This local quality change allows the housing to remain stable during normal use but fracture predictably during tampering attempts, providing clear tamper indication.
3Reliability
If the frangible seal is the only tamper indication mechanism, then the seal provides clear tamper evidence, but the device can still be removed by popping the rivets without affecting the seal
Solution Approach 1:
The area of weakness is strategically positioned and designed to fail in advance of any attempt to remove the device by prising. This preliminary failure mode prevents the harmful action of clean device removal by ensuring that any prising force will first cause fracture of the housing or area of weakness, making tampering evident before the device can be removed.
Data Source
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AI summary
The invention relates to a security device (10) for a container such as a bag or envelope closeable by a slide fastener having a slider (16). The security device (10) includes a lower part (12) for attachment to the container and means (14) for attaching the security device (10) to the slider (16), directly or indirectly. An upper part (20) retains the attaching means (14). Receiving means (24) can receive a frangible seal (26) and prevent retraction of the frangible seal (26), except by fracture thereof. Means (28) limits access to the attaching means (14) and the receiving means (24). The security device (10) includes an area of weakness (30) adapted to fracture if the security device (10) is prised from the container.