Earphone Button Detection Circuit Using Resistor-Comparator Voltage Measurement
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Solution Overview
Problem
Noise reduction earphones with a four-conductor plug pose a risk of circuit burnout due to direct short-circuiting when a button is pressed, as the microphone line is used as both a power and signal line, making it difficult to detect button actions without causing damage.
Innovation Solution
A circuit incorporating a first and second resistor, a comparator, and a microphone connected to a power supply, where the button is connected between the microphone and the second resistor, allowing for voltage difference detection to determine the button state without direct grounding, thus preventing burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the button is implemented by short-circuiting the MIC line in a noise reduction earphone with a four-conductor plug, then the button detection function is achieved, but the power line is directly short-circuited to ground causing circuit burnout
Solution Approach 1:
The patent introduces a detection circuit with resistors (R1, R2) and a comparator as intermediary components between the button and the MIC line. When the button is pressed, instead of directly short-circuiting the power line to ground, the circuit measures voltage changes through the resistors and comparator, thereby detecting the button state without causing direct short-circuit damage.
Solution Approach 2:
The patent replaces the direct electrical short-circuit mechanism with an electrical measurement system. Instead of using a mechanical switch that directly connects power to ground, the invention uses voltage detection through resistors and a comparator to sense the button state, substituting a dangerous direct electrical connection with a safe measurement-based detection method.
2Adaptability or versatility
If the MIC line is used as both power line and signal line, then the earphone can be charged through the MIC line, but pressing the button causes direct grounding of power supply leading to circuit burnout
Solution Approach 1:
The patent introduces detection circuit components (resistors R1 and R2, comparator) as intermediaries between the MIC line and ground. These components create a safe measurement path that allows button detection while preventing direct power grounding, thus enabling dual-use of the MIC line without the harmful short-circuit effect.
Solution Approach 2:
The patent预先 (in advance) protects the circuit by placing resistors and a comparator in the detection path before the button can cause a direct short-circuit. This preemptive protective structure ensures that even when the button is pressed, the power line cannot be directly grounded, thus cushioning against the potential harmful effect before it can occur.
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
Enables safe detection of button states in noise reduction earphones by maintaining resistance between the button and power supply, preventing circuit burnout and allowing for corresponding functions to be executed based on the detected state.
Implementation Method 1
a comparator, provided with a first input end, a second input end, and an output end, where the first input end of the comparator is connected to the first end of the first resistor, and the second input end of the comparator is connected to the second end of the first resistor; and configured to output a control signal at the output end of the comparator when a voltage difference between the first input end and the second input end is greater than a first threshold
Data Source
AI summary
A circuit for detecting a button action on an earphone, including a first resistor, a comparator having with a first input end, a second input end, and an output end, with the first input end of the comparator connected to the first end of the first resistor, and the second input end of the comparator connected to the second end of the first resistor. A power supply us connected to the first resistor. The earphone includes a second resistor, and when the earphone is connected to the circuit, the second resistor is connected to the first resistor. The earphone further includes a microphone having a first end connected to the first end of the second resistor and a second end grounded, and a button having ends that are respectively connected the microphone and the second resistor. When the button is pressed, the ends of the button are connected.