Shielding Container for Keyfob H-Field Signal Attenuation
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Solution Overview
Problem
Conventional window-mounted lockboxes are ineffective in preventing the activation of passive keyless entry keyfobs due to penetration of wireless signals, leading to unauthorized vehicle access.
Innovation Solution
A container designed to attenuate low-frequency signals, such as H-field signals, to prevent the keyfob from being activated by external wireless signals, maintaining it in a sleep state and thus conserving battery life and preventing unauthorized use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lockbox is used to store the keyfob, then the keyfob is physically secured, but wireless signals can penetrate the lockbox and activate the keyfob
Solution Approach 1:
The lockbox incorporates electromagnetic shielding material (such as conductive fabric or metal mesh) integrated into the box structure to block wireless signals while maintaining physical access functionality. This composite construction prevents signal penetration that would otherwise activate the keyfob inside.
Solution Approach 2:
An electromagnetic shielding layer acts as an intermediary between the external wireless environment and the keyfob inside the lockbox. This intermediate barrier absorbs or reflects radio frequency signals, preventing them from reaching the keyfob antenna and causing activation.
2Ease of operation
If the keyfob remains active within communication range, then vehicle access is convenient, but battery life is reduced and unauthorized access risk increases
Solution Approach 1:
The lockbox with electromagnetic shielding proactively prevents the keyfob from being activated by external signals before unauthorized access can occur. By blocking the wakeup signals in advance, the system maintains security while allowing the keyfob to remain in sleep mode, conserving battery power.
Solution Approach 2:
The shielding material that initially seemed to block legitimate access signals is configured to block all wireless communications equally. This converts the potential harm of signal interference into a benefit by preventing both unauthorized activation and accidental wakeups, extending battery life while maintaining controlled access.
3Object-affected harmful factors
If the lockbox is made more shielded to block signals, then keyfob activation is prevented, but signal attenuation may also block legitimate access when needed
Solution Approach 1:
The electromagnetic shielding is applied selectively to specific areas of the lockbox structure where signal penetration is most problematic, rather than using complete opaque shielding. This localized approach blocks harmful activation signals while allowing controlled signal transmission through designated access points when the box is properly opened.
Solution Approach 2:
The lockbox shielding system incorporates dynamic characteristics where the electromagnetic blocking properties change based on the box state. When the lid is opened or the box is removed from the vehicle, the shielding effectiveness is reduced or disabled, allowing legitimate keyfob activation for authorized access.
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 container effectively shields the keyfob from external wireless signals, preventing unauthorized vehicle access and improving battery life by maintaining the device in a sleep state, even when within the vehicle's communication range.
Implementation Method 1
Embodiments of the container disclosed herein, attenuate low frequency signals, like low frequency H-field signals ('H-field signals') that have a frequency of about 100 KHz to about 200 KHz
Data Source
AI summary
An improved container configured to store a wireless-enabled device therein and also configured to prevent the wireless-enabled device from being activated by an external wireless signal.