Vehicle Speaker Failure Detection Using DC Test Current
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Solution Overview
Problem
Existing vehicle speaker failure detection devices are cumbersome, costly, and unable to detect open-circuits or short-circuits during normal operation, requiring multiple components and AC signal generators, and often consume unnecessary power.
Innovation Solution
A compact failure detection device for vehicle speakers that includes a signal generator, amplifier, coupling capacitor, supply circuit, and detection circuit, capable of detecting open-circuits and short-circuits during normal operation using a direct-current test current and threshold voltage comparison, without requiring an AC signal generator and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing failure detection devices use current transformers and voltage transformers on the speaker line, then open-circuit detection is achieved, but the number of parts, size, and cost increase
Solution Approach 1:
The patent combines the failure detection function with the existing amplifier circuit by integrating a detection circuit that shares the same power supply and signal path. The determination section uses the existing amplifier output to detect open-circuits, eliminating the need for separate current transformers and voltage transformers, thus reducing the number of parts while maintaining detection reliability
Solution Approach 2:
The amplifier circuit is designed to serve dual purposes: amplifying the audio signal for speaker output and simultaneously providing the detection voltage for open-circuit detection. The detection circuit uses the same power supply and signal path as the amplifier, making the system multi-functional and reducing overall component count
2Reliability
If equivalent circuit with equivalent impedance is used for open-circuit detection, then detection capability is achieved, but the number of parts and size increase
Solution Approach 1:
The detection circuit is merged with the amplifier circuit, sharing the same housing and power supply. The determination section is integrated into the amplifier's control unit, eliminating the need for separate detection devices and reducing overall system size
3Difficulty of detecting and measuring
If AC signal of inaudible frequency is mixed with audible signal for testing, then speaker line detection is achieved, but an AC signal generator and additional amplification are required
Solution Approach 1:
The patent extracts the detection function from the audio signal path by using a separate detection circuit that applies a test voltage independently. This allows the audible audio signal to pass through unchanged while the detection circuit separately measures the speaker's electrical characteristics, eliminating the need to mix inaudible test signals with the audio output
Solution Approach 2:
The detection circuit acts as an intermediary that applies a test voltage through a test terminal separate from the audio signal path. This intermediary measurement approach allows the speaker's electrical properties to be measured without interfering with the audio output, eliminating the need for complex signal mixing and additional amplification
4Use of energy by stationary object
If detection voltage is supplied only when detection is performed, then power consumption is reduced, but failure detection during normal operation is not possible
Solution Approach 1:
The detection circuit is designed to continuously monitor the speaker's electrical characteristics during normal operation by utilizing the existing amplifier output as the detection voltage source. This preliminary continuous monitoring enables failure detection without requiring separate detection cycles, and the system only consumes additional power when actual detection measurements are performed
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 enables efficient and cost-effective detection of speaker failures during normal operation, reducing the number of components and power consumption while maintaining the tone of the notification sound, thus enhancing operational reliability and reducing costs.
Implementation Method 1
a coupling capacitor (5) that supplies the amplified sound signal to the speaker (2)
Implementation Method 2
The detection circuit detects a terminal voltage on a terminal of the speaker
Data Source
AI summary
A failure detection device for a vehicle speaker includes a signal generator, an amplifier, a coupling capacitor, a supply circuit, a detection circuit, and a determination section. The signal generator generates a sound signal corresponding to sound outputted from the speaker. The amplifier amplifies the sound signal. The capacitor supplies the amplified sound signal to the speaker. The supply circuit supplies a direct-current test current to the speaker so that the test current does not flow through the capacitor by applying a test voltage to the speaker. The test voltage is higher than a voltage of the sound signal. The detection circuit detects a terminal voltage of the speaker. The determination section determines whether at least one of an open-circuit and a short-circuit occurs in the speaker based on the terminal voltage during application of the sound signal to the speaker.