Acoustic-Electric Transducer Mute State Connection Detection

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Solution Overview

Problem

Conventional acoustic-electric transducers in mute state do not allow current flow, preventing connection detection by terminals, which fail to recognize the microphone or headset as connected.

Innovation Solution

Incorporating a current control circuit with a capacitor and field effect transistor that charges and switches states to allow initial connection detection and then enters a high impedance state, ensuring the terminal can detect the transducer even in mute mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the acoustic-electric transducer is in mute state, then the audio output is muted, but the terminal cannot detect the connection of the transducer

Engineering Contradiction:
Improveconnection detection capabilityVSAvoidmute state functionality
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by enabling the current control circuit to proactively establish a temporary conductive state upon connection, allowing the terminal to detect the transducer before the circuit transitions to its normal high-impedance mute state. This preliminary current flow action ensures connection detection capability is preserved even when the transducer operates in mute state.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the impedance state of the current control circuit time-variable: it transitions from a high-impedance state (during normal mute operation) to a temporary low-impedance conductive state (upon connection detection), and then returns to high-impedance state. This dynamic impedance switching enables both mute functionality and connection detection to coexist.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the acoustic-electric transducer allows current flow for connection detection, then the terminal can detect connection, but the transducer cannot maintain high impedance state for proper signal processing

Engineering Contradiction:
Improveconnection detection capabilityVSAvoidelectrical signal characteristics
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies periodic action through the time-controlled switching behavior of the current control circuit, which periodically transitions between high-impedance and low-impedance states. The circuit maintains high impedance during normal operation for proper signal processing, temporarily switches to low impedance for connection detection, and then returns to high impedance, creating a controlled periodic impedance profile that satisfies both requirements.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent uses preliminary action by having the current control circuit perform a temporary low-impedance state action immediately upon connection, before the transducer begins its normal high-impedance signal processing operation. This preliminary current flow enables connection detection without interfering with the subsequent precision signal processing requirements.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the changeover switch is in off state, then the transducer is in mute state, but no current flows through the transducer for connection detection

Engineering Contradiction:
Improvemute state controlVSAvoidconnection detection function
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces the current control circuit as an intermediary component between the changeover switch and the acoustic-electric transducer. This intermediary circuit can independently control the impedance state and current flow, allowing it to temporarily bypass the off state of the changeover switch to enable connection detection current flow, while still respecting the mute state control when in normal operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 the terminal to accurately detect the acoustic-electric transducer's connection, regardless of its mute state, without affecting the electrical signal characteristics.

Implementation Method 1

a capacitor that is charged by a current supplied from the terminal, and an electronic switch that sets a state between a first connection point and a second connection point to a conductive state until the capacitor is completely charged

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

an electronic switch that sets a state between a first connection point and a second connection point to a conductive state until the capacitor is completely charged, and sets the state between the first connection point and the second connection point to a non-conductive state after the predetermined time passes

Methodology Applied
Scientific EffectField effect transistor operation:

Data Source

PatentEP3755002B1Acoustic-electric transducer with changeover switch for mute state
Publication Date: 2024.12.11 AUDIO TECHNICA CORP
  • EP3755002B1 patent drawingFigure 1
  • EP3755002B1 patent drawingFigure 2
  • EP3755002B1 patent drawingFigure 3(a)~3(b)

AI summary

An acoustic-electric transducer 1 includes a connection part 13 that has a first connection point 131 able to contact a first contact A in a terminal 2 for processing the electrical signal, and a second connection point 132 able to contact a second contact B having a potential lower than the potential of the first contact A, a microphone 101 that transduces a sound inputted from an external source into an electrical signal, a changeover switch 11 that switches between a non-mute state where the electrical signal is outputted to the terminal 2 and a mute state where the electrical signal is not outputted to the terminal 2, and a current control circuit 14 that makes a current flow between the first contact A and the second contact B until a predetermined time passes from the time when the connection part 13 is connected to the terminal 2 and reduces the current flowing between the first contact A and the second contact B after the predetermined time passes, the current control circuit 14 being provided between the changeover switch 11 and the connection part 13.