Silent Buzzer Fault Detection via Capacitance Measurement
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Solution Overview
Problem
Existing methods for fault testing buzzers in hazard detection systems, such as smoke and CO detection, face challenges in ensuring the buzzer functions properly without causing a false alarm, as regulations require silent testing to avoid audible sounds during fault detection.
Innovation Solution
A semiconductor device and method that utilize a buzzer driver, current generator, and analog-to-digital converter to perform silent fault testing by disconnecting the buzzer from ground, generating a test current, and measuring capacitance values without physically disconnecting the buzzer, ensuring no audible sound is produced during the test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault testing is performed to confirm buzzer functionality, then reliability of hazard detection system is improved, but false alarm condition occurs due to audible sound generation
Solution Approach 1:
The patent introduces an intermediary measurement system consisting of a current generator, analog-to-digital converter, and processing device that indirectly assesses buzzer functionality through electrical characteristics (capacitance measurements) rather than direct acoustic output. This mediator enables fault detection without triggering the buzzer's audible alarm function.
Solution Approach 2:
The patent replaces the mechanical/acoustic testing method (directly activating the buzzer and listening for sound) with an electrical measurement system. By substituting the acoustic detection mechanism with electrical capacitance measurements, the system can assess buzzer integrity without producing audible sound, thereby preventing false alarms while maintaining reliability verification.
2Reliability
If buzzer is activated for fault testing, then functionality is verified, but audible sound is generated causing false alarm
Solution Approach 1:
The patent extracts the measurement function from the buzzer's primary alarm function. By separating the functionality verification process from the audible output mechanism, the system can test buzzer integrity through electrical measurements while leaving the acoustic generation disabled, thus verifying reliability without generating harmful audible sound.
Solution Approach 2:
The patent changes the measurement parameter from acoustic output (sound pressure level, frequency) to electrical characteristics (capacitance, current flow). By measuring electrical parameters during a test cycle instead of acoustic parameters, the system verifies buzzer functionality while preventing audible sound generation that would cause false alarms.
3Object-affected harmful factors
If silent fault testing is performed, then false alarm is prevented, but measurement complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing measurement circuitry that can operate in multiple modes: normal operation mode and fault testing mode. The same current generator and analog-to-digital converter serve both regular system operation and silent fault detection, reducing overall device complexity despite the added measurement capabilities.
Solution Approach 2:
The patent enables the system to perform self-diagnosis through integrated measurement capabilities. The processing device automatically initiates fault testing cycles, performs capacitance measurements, and determines buzzer status without external intervention, thereby managing the increased measurement complexity through automated self-service operations.
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 in-situ, silent fault detection of buzzers, preventing false alarms while ensuring the buzzer's functionality, thus meeting regulatory requirements for hazard detection systems.
Implementation Method 1
a current generator that is configured to supply a test current to a given output pin of the plurality of output pins
Implementation Method 2
initiating analog-to-digital conversion by an analog-to-digital converter connected to the buzzer via the given output pin to generate count values
Data Source
AI summary
In an embodiment, a semiconductor device is disclosed. The semiconductor device includes a plurality of output pins. Each of the output pins is electrically connected to an input pin of a buzzer and to a buzzer driver. The buzzer driver is configured to cause the buzzer to emit an audible sound. The semiconductor device further includes a plurality of ground switches. Each ground switch is configured to connect a corresponding output pin of the plurality of output pins to ground when closed. The semiconductor device further includes a current generator that is configured to supply a test current to a given output pin of the plurality of output pins and a clamp switch that is configured to connect the given output pin to an analog-to-digital converter.