Socket Detection Circuit Using Variable Resistance to Distinguish Plug from Moisture
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Solution Overview
Problem
Existing plug detection systems in electronic devices face issues with distinguishing between an electrical plug and moisture in sockets, leading to incorrect plug detection and potential audible artefacts or device malfunction due to moisture-induced electrical connections.
Innovation Solution
A circuit with a variable resistance connected between two voltage nodes, controlled by a detection and control circuit, which adjusts resistance values to differentiate between plug and moisture presence based on voltage levels, allowing accurate plug detection without lengthy impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a weak pull up resistor is used to detect plug insertion by monitoring voltage changes, then plug detection is enabled, but moisture in the socket can cause false detection as moisture creates sufficient electrical connection to pull voltage to ground
Solution Approach 1:
The patent applies dynamics by making the resistance value time-variable. A timer circuit controls a switch that alternates between connecting a low resistance path (for moisture detection) and a high impedance state (for normal operation). This dynamic switching allows the system to adapt its detection characteristics over time, enabling distinction between transient moisture effects and permanent plug insertion.
Solution Approach 2:
The patent changes the electrical resistance parameter dynamically. By switching between different resistance values (high and low) at different time intervals, the system creates distinct voltage signatures for moisture versus plug insertion. The parameter change is controlled by a timer that periodically modifies the resistance connected to the detection node.
2Measurement precision
If impedance measurement is performed to distinguish moisture from plug, then detection accuracy improves, but the measurement process is lengthy and consumes significant current
Solution Approach 1:
The patent implements periodic action through a timer-based switching mechanism. Instead of continuous impedance measurement, the system periodically switches the resistance value at predetermined intervals. This pulsed detection approach dramatically reduces average current consumption while still providing sufficient data points to distinguish between moisture and plug insertion events.
Solution Approach 2:
The patent uses a simple resistive switching mechanism rather than complex continuous impedance measurement circuitry. The detection relies on brief periodic voltage samples taken during resistance transitions, effectively using short-lived measurement events instead of sustained measurement processes, thereby reducing energy consumption.
3Reliability
If continuous monitoring with high current is used to ensure accurate detection, then detection reliability improves, but power consumption increases
Solution Approach 1:
The system performs detection periodically rather than continuously. A timer generates periodic signals that switch the resistance value, and voltage is sampled only during these periodic events. This approach maintains detection reliability by regularly monitoring the socket state while minimizing power consumption by keeping the detection circuit in a low-power state between measurements.
Solution Approach 2:
The detection circuit uses the existing voltage at the detection node, which is naturally present due to the pull-up resistor and socket conditions. The system leverages this existing electrical state rather than requiring active high-current driving, allowing reliable detection through passive voltage monitoring combined with periodic resistance switching.
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 distinguishes between plug and moisture presence, reducing audible artefacts and preventing device malfunction by accurately detecting plug insertion/removal even in the presence of moisture, without continuous high current consumption.
Implementation Method 1
moisture in the socket in the absence of a plug may cause a sufficient electrical connection between the socket connectors and cause the voltage at the first socket connectors to be pulled close enough to ground to be interpreted as a plug being inserted
Data Source
AI summary
Circuits for monitoring a socket are disclosed, including a circuit comprising a first node arranged to be electrically connected to a first pole of an electrical plug when the electrical plug is inserted into a corresponding socket, a second node arranged to be connected to a first voltage, wherein the first node is arranged to be connected to the first pole when the electrical plug is inserted into the socket, a variable resistance connected between the first node and a third node, wherein the third node is arranged to receive a second voltage, detection circuit arranged to detect the presence of the electrical plug or moisture in the socket based on a voltage at the first node, and a control circuit arranged to control the variable resistance to a first resistance value and, in response to the detection circuit detecting the presence of the electrical plug or moisture in the socket when the variable resistance is at the first resistance value, to a second resistance value, whereby the detection circuit distinguishes between the electrical plug and moisture within the socket.