Vehicle Warning Speaker Failure Detection via Monitor Voltage
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Solution Overview
Problem
Existing vehicle approach warning apparatuses face challenges in accurately detecting speaker failures, particularly short-circuit and open-circuit failures, due to the amplification of external noise, which can reduce the accuracy of failure detection.
Innovation Solution
The apparatus incorporates a monitor voltage output circuit that half-wave rectifies and integrates the warning signal during sound emission periods to differentiate between normal and failed speaker conditions, reducing the need for high amplification and minimizing noise interference, and uses a microcomputer to determine failure based on specific voltage waveforms during sound and non-sound emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resistance of the detection resistor is increased to improve failure detection voltage, then the speaker current decreases and output sound pressure decreases
Solution Approach 1:
The patent introduces a detection resistor as an intermediary component inserted in series with the speaker. This resistor converts the speaker current into a detectable voltage signal that can be monitored by the control unit, enabling failure detection without significantly impacting the speaker's output performance.
Solution Approach 2:
The patent replaces direct monitoring of speaker current with voltage monitoring across the detection resistor. This substitution allows the control unit to detect speaker failures by measuring voltage changes rather than directly measuring current, improving detection capability while maintaining speaker performance.
2Power
If the resistance of the detection resistor is decreased to maintain output sound pressure, then the monitored voltage decreases and detection accuracy is reduced
Solution Approach 1:
The patent dynamically adjusts the detection strategy by having the control unit monitor the voltage across the detection resistor during sound emission periods and compare it against reference values. This dynamic monitoring approach allows for accurate failure detection even with low resistance values that maintain speaker output pressure.
Solution Approach 2:
The control unit continuously monitors the voltage across the detection resistor and uses this feedback to determine speaker status. By comparing the monitored voltage with expected voltage ranges during sound emission, the system can detect failures while maintaining optimal speaker performance through appropriate resistance selection.
3Measurement precision
If a large amplifier gain is used to amplify the monitored voltage for better detection, then external noise is also amplified and detection accuracy is reduced
Solution Approach 1:
The patent optimizes the detection by monitoring voltage during specific sound emission periods when the warning sound is actively being emitted. By timing the detection to coincide with known sound emission intervals, the system can distinguish between expected voltage changes during normal operation and actual failure conditions, reducing false detections from noise.
Solution Approach 2:
The control unit is configured to monitor the detection resistor voltage in advance during sound emission periods and immediately detect failures when voltage anomalies occur. This preliminary monitoring approach allows for rapid failure detection before noise accumulation can significantly impact detection accuracy.
4Device complexity
If the speaker current is monitored directly to detect failures, then the system is simple, but external noise on the output wire reduces detection accuracy
Solution Approach 1:
The detection resistor serves as an intermediary that converts speaker current into a voltage signal that can be monitored with higher accuracy. This intermediary component allows the system to detect failures by measuring voltage across the resistor rather than directly measuring current on the noisy output wire, improving detection accuracy while maintaining system simplicity.
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 enhances the accuracy of detecting both short-circuit and open-circuit failures in the speaker, reducing the impact of external noise and allowing for timely reporting of failures to the user, thereby ensuring pedestrian safety.
Implementation Method 1
the monitor voltage output circuit outputs the monitor voltage from an output terminal by half-wave rectifying and integrating the warning signal
Implementation Method 2
the monitor voltage output circuit outputs the monitor voltage from an output terminal by half-wave rectifying and integrating the warning signal
Data Source
AI summary
A vehicle approach warning apparatus has a failure determining section and a monitor voltage output circuit connected to a potential change terminal. During a sound emit period where a warning signal is being outputted to an sound emitter for emitting a warning sound, the output circuit outputs a monitor voltage from an output terminal by half-wave rectifying and integrating the warning signal upon a change of a potential of the potential change terminal to a high level. When a short-circuit failure occurs in the sound emitter, the output circuit keeps a potential of the output terminal to a low level during the sound emit period. During the sound emit period, the failure determining section sets the potential of the potential change terminal to a high level and determines whether the short-circuit failure occurs based on the monitor voltage.