Tamper Detection Box with Randomized Code Wheel
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Solution Overview
Problem
Existing electricity meter designs fail to reliably detect unauthorized access to the terminal strip, especially during power outages, as fraudulent individuals can reset the code wheel before power is restored, allowing undetected tampering.
Innovation Solution
A box with a movable cover equipped with an electronic detection circuit and a screw-end tooth mechanism that provides radial clearance to the code wheel, combined with a pawl and audible click mechanisms, ensuring the code wheel's position is randomized and cannot be easily reset, and emitting clicks to mask any noise from the pawl, thus enhancing detection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a code wheel with teeth is used to detect cover opening, then the detection mechanism is simple and reliable, but a fraudulent person can reset the code wheel by causing it to revolve through one complete revolution before power is restored
Solution Approach 1:
The patent applies preliminary action by storing the position of the code wheel relative to the detection circuit pads each time the meter is powered. This pre-stored position information enables the system to detect any subsequent movements of the code wheel, including fraudulent complete revolutions, by comparing the current position against the stored reference position when power is restored.
Solution Approach 2:
The patent implements feedback through a detection circuit that continuously monitors the position of the code wheel teeth relative to fixed pads. The circuit provides feedback signals when teeth align with pads, enabling the system to detect and record code wheel movements. This feedback mechanism ensures that any unauthorized resetting attempts are captured and reported.
2Reliability
If orifices are provided in the cover to pass a lead-sealed wire, then tampering can be detected, but technician visits become rarer due to remote meter reading development
Solution Approach 1:
The patent replaces the mechanical lead-sealed wire system with an electronic detection circuit that uses electrical contacts between code wheel teeth and fixed pads. This substitution eliminates the need for physical seal breaking and technician visits, as the electronic system continuously monitors cover status and can detect tampering remotely through power consumption patterns or communication modules.
Solution Approach 2:
The patent enables self-service by implementing an autonomous detection system that automatically monitors cover opening without requiring technician intervention. The detection circuit operates independently, storing position data and generating detection signals when the cover is moved, thereby eliminating the need for rare technician visits while maintaining security.
3Extent of automation
If a switch is placed in the box to be actuated by the screw, then tampering can be detected without technician action, but the meter must be powered for detection to work
Solution Approach 1:
The patent applies preliminary action by storing the code wheel position data in memory each time the meter is powered. This pre-stored information remains available even during power outages, enabling the system to detect any subsequent code wheel movements by comparing current position against the stored reference when power is restored, thus maintaining detection capability during power interruptions.
Solution Approach 2:
The patent replaces the powered switch mechanism with a passive code wheel and detection circuit that uses mechanical tooth-pad contacts. This mechanical-electrical hybrid system does not require active power for the detection mechanism itself, as the teeth and pads create electrical connections passively when the code wheel moves, enabling detection during power outages.
Data Source
AI summary
A box comprising at least one portion that is closed by a movable cover and that contains an electronic detection circuit for detecting opening of the cover, the cover being provided with means for locking it in the closed position, said means comprising a screw that is mounted on the cover to pivot between a locking position and an unlocking position, and having an end provided with at least one tooth for meshing with teeth of a code wheel mounted to pivot in register with pads of the detection circuit, wherein the screw is mounted so that said end of the screw presents positioning with radial clearance relative to the box in such a manner that the pivoting of the code wheel has an amplitude that depends on the positioning of said end as authorized by the radial clearance.