Inductive Resonant Wake-Up Circuit for Security Readers
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Solution Overview
Problem
Security devices often consume unnecessary power due to false wake-ups from capacitive objects, which is inefficient and undesirable.
Innovation Solution
A security device with an inductively coupled resonant wake-up module that detects credential devices by changes in the electromagnetic field, only waking up when a credential device with a matching resonant frequency is present, minimizing false activations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive wake-up circuit is used, then the device can detect objects and wake up from sleep mode, but any capacitive object causes false wake-ups and increases power consumption
Solution Approach 1:
The patent changes the detection parameter from capacitive coupling to inductive coupling with resonant frequency matching. The wake-up module uses an inductively coupled resonant circuit that detects credential devices through inductive coupling at a specific resonant frequency, rather than through capacitive coupling. This parameter change ensures that only objects with the matching resonant frequency will trigger a wake-up event, eliminating false wake-ups from non-credential capacitive objects while maintaining reliable detection of authorized devices.
2Speed
If the device remains in active mode continuously, then it can immediately read credential information, but power consumption increases significantly
Solution Approach 1:
The patent implements periodic action by allowing the reader to enter sleep mode during periods when no credential device is present, and waking up only when needed. The inductively coupled resonant wake-up module continuously monitors for credential devices at low power consumption, and when a credential device is detected through resonant frequency matching, the reader is awakened to perform the reading operation. This periodic sleep-wake cycle significantly reduces power consumption while maintaining the ability to respond immediately when a credential device is presented.
3Device complexity
If a simple wake-up circuit is used, then device complexity is low, but false wake-ups from non-credential objects occur frequently
Solution Approach 1:
The patent applies the principle of resonance by using an inductively coupled resonant circuit that operates at a specific resonant frequency. The wake-up module includes a resonant circuit that generates an electromagnetic field at a predetermined resonant frequency, and detects credential devices that resonate at this same frequency. This resonant frequency matching creates a selective detection mechanism that is inherently more reliable than simple capacitive coupling, as it responds only to objects with the specific resonant characteristics of credential devices, thereby improving wake-up accuracy without requiring overly complex circuitry.
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
This approach significantly reduces power consumption by ensuring the device only wakes up when an authorized credential device is near, avoiding unnecessary power usage and enhancing energy efficiency.
Implementation Method 1
A wake-up module includes an inductively coupled resonant circuit. The wake-up module is configured to detect a credential device near the reader if the credential device has a resonant frequency corresponding to a frequency of an electromagnetic field of the inductively coupled resonant circuit
Implementation Method 2
detect a credential device near the reader if the credential device has a resonant frequency corresponding to a frequency of an electromagnetic field of the inductively coupled resonant circuit
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
An exemplary security device includes a reader configured to read information stored on a credential device. The reader enters a sleep mode when not reading a credential device. A wake-up module includes an inductively coupled resonant circuit. The wake-up module is configured to detect a credential device near the reader if the credential device has a resonant frequency corresponding to a frequency of an electromagnetic field of the inductively coupled resonant circuit that is controlled by a stable oscillator. The wake-up module is configured to provide an indication to wake-up the reader from the sleep mode responsive to detecting a change in power of the electromagnetic field caused by the credential device.