Capacitive Coupling Motor Driver for Secure Lock Actuation
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Solution Overview
Problem
Access control systems face security vulnerabilities due to potential failures in motor control mechanisms, particularly from external impacts like lightning or voltage manipulation, which can compromise the reliability and security of electronic locks.
Innovation Solution
A lock device with a controller that generates a pulsating signal with a duty cycle less than a threshold, utilizing a motor driver with capacitive coupling to prevent pure DC signals from reaching the motor, ensuring that only a pulsating signal can activate the motor, thereby enhancing security and reliability by limiting energy transfer and preventing unauthorized activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor control mechanism is used to open the lock device, then the lock device can be opened when access is granted, but the system becomes vulnerable to external impacts such as lightning or voltage manipulation that can cause unauthorized activation
Solution Approach 1:
The patent applies preliminary anti-action by implementing a capacitive coupling circuit that proactively prevents DC signals from reaching the motor. The capacitor is configured to block pure DC signals before they can cause unauthorized motor activation, thereby preemptively countering potential harmful effects from external impacts or controller failures.
Solution Approach 2:
The patent uses an intermediary element (capacitor) placed between the controller output and the motor. This capacitor acts as a mediator that allows pulsating signals to pass through while blocking pure DC signals, thus protecting the motor from unauthorized activation without interfering with normal lock operation.
2Reliability
If a constant high DC signal is provided to the motor driver due to controller failure, then the motor driver receives continuous power, but this results in unauthorized motor operation compromising security
Solution Approach 1:
The capacitive coupling circuit is designed to preemptively block DC signals that could result from controller failures. By placing the capacitor in series with the motor driver input, the system proactively prevents DC signal propagation, ensuring that even if the controller fails and outputs a constant high DC signal, the motor cannot be activated.
3Reliability
If the duty cycle threshold is set to prevent unauthorized activation, then security is improved, but the system complexity increases due to the need for duty cycle monitoring and comparison
Solution Approach 1:
The patent replaces complex active duty cycle monitoring circuits with a passive capacitive coupling approach. Instead of using active components to monitor and compare duty cycles, the system uses the inherent properties of the capacitor to naturally filter out DC signals, significantly reducing circuit complexity while maintaining security.
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 solution effectively prevents unauthorized motor activation and maintains the lock in a secure closed state even if the controller fails, enhancing the overall security and reliability of the access control system by ensuring that only a pulsating signal with a specific duty cycle can open the lock.
Implementation Method 1
a motor driver connected between the controller and the motor, the motor driver comprising a capacitor providing a capacitive coupling between the controller and the motor
Data Source
Figure 1~2B
Figure 3~5B
Figure 6A~7
AI summary
It is presented a lock device comprising: a controller configured to determine whether to open the lock device, wherein the controller is configured to provide an open signal when the lock device it to be opened, the open signal being a pulsating signal; a motor controllable to set the lock device in an open state or a closed state; and a motor driver connected between the controller and the motor, the motor driver comprising a capacitor providing a capacitive coupling between the controller and the motor, the motor driver being configured to provide a motor control signal to the motor to set the lock device in an open state only when a duty cycle of the open signal is less than a threshold duty cycle.