Magnetic Lock Anti-Defeat Impact Protection

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Solution Overview

Problem

Magnetic locks in security tags are vulnerable to unauthorized unlocking when subjected to impact forces, such as being dropped or slammed, due to the compression of springs that momentarily transition the lock to an unlocked state.

Innovation Solution

The implementation of an anti-defeat structure within the security tag, which includes an impact mass and an impulse spring, absorbs impact energy and applies a reactionary impulse force to maintain the plunger's engagement with the latch, preventing unlocking during impacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spring is used to retain the lock in a latched condition, then the lock can be released by applying force, but the spring compresses under impact force causing momentary unlocking

Engineering Contradiction:

Improvelock releaseVSAvoidlock security

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces a resilient member (spring) that is pre-compressed to provide cushioning against impact forces. This spring absorbs the shock of impact before it can reach the locking mechanism, preventing the plunger from being pushed out of engagement with the latch during accidental drops or impacts.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent modifies the force parameters by introducing a threshold mechanism. The locking mechanism is designed to respond only to forces exceeding a specific threshold (intentional release force), while filtering out lower-magnitude forces (impact forces). This is achieved through the combined action of the resilient member and the geometric design of the plunger-latch interface.

Inventive Principle:

Principle #35Parameter changes

2Strength

If a magnetic locking mechanism is used, then the tag can be securely locked, but it becomes vulnerable to unauthorized unlocking by impact forces

Engineering Contradiction:

Improvelocking strengthVSAvoidimpact vulnerability

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful impact force into a beneficial filtering mechanism. The resilient member is designed to compress under impact forces, and this compression is used to detect and reject unauthorized release attempts. The system distinguishes between harmful impacts (which compress the spring) and legitimate release attempts (which overcome the spring force through the detaching unit).

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the spring force is increased to prevent impact unlocking, then lock security improves, but the force required for legitimate release increases

Engineering Contradiction:

Improvelock securityVSAvoidrelease force

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent segments the force response into two distinct phases: (1) Impact phase, where the resilient member absorbs low-magnitude forces through compression, and (2) Release phase, where the detaching unit applies high-magnitude force to overcome the pre-compressed spring. This segmentation allows the system to use a stronger spring for security without increasing the operational difficulty, because the detaching unit is specifically designed to deliver the necessary force to overcome the pre-compressed spring state.

Inventive Principle:

Principle #1Segmentation

4Strength

If a mechanical locking mechanism is used, then the tag can be securely attached, but it can be defeated by striking the tag on a surface

Engineering Contradiction:

Improveattachment strengthVSAvoidimpact defeat

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by pre-compressing the resilient member during the locking process. This pre-compression creates a counter-force that opposes impact forces before they can cause unlocking. The plunger is held in engagement with the latch by the pre-compressed spring, creating a state of preliminary resistance against unauthorized release attempts.

Inventive Principle:

Principle #9Preliminary anti-action

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 anti-defeat structure effectively prevents the magnetic lock from being unlocked by impact forces, ensuring the security tag remains locked and secure even when subjected to drops or other impacts.

Implementation Method 1

absorbs impact energy and applies a reactionary impulse force

Methodology Applied

Scientific EffectImpact force: Impact Force

Implementation Method 2

an impulse spring, absorbs the shock

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 3

application of a magnetic field by a magnet

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentUS12286818B2Magnetically-locking retractable tag with anti-defeat impact protection

Publication Date: 2025.04.29 SENSORMATIC ELECTRONICS CORP

AI summary

Systems and methods for operating a security tag. The methods comprise: causing a plunger of the security tag to engage a latch of the security tag; preventing, by an anti-defeat structure of the security tag, a disengagement between the plunger and the latch when an impact force is applied to the security tag; and allowing, by the anti-defeat structure, the plunger to disengage the latch when a magnetic field is applied to the security tag.