Piezoelectric Window Sensor High-Pass Filtering Glass Break
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Solution Overview
Problem
Existing sensors fail to reliably distinguish between a broken window and other events, such as a bouncing ball, due to similar vibration data patterns.
Innovation Solution
A sensor device with a vibration detector attached to the windowpane and a separate sensor controller that uses high-pass filtering to differentiate between vibrations above a threshold frequency (e.g., 20 kHz) to detect shattered glass, and includes a proximity detector to determine the window's status, with a power-efficient combination of piezoelectric and accelerometer sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If normal accelerometers are used in window frames, then the device can detect vibrations, but the detection precision is insufficient to distinguish between broken windows and other events like bouncing balls
Solution Approach 1:
The patent changes the detection parameter from general vibration amplitude to high-frequency vibration content above 20 kHz. By filtering and analyzing only the high-frequency component of vibrations, the system achieves sufficient precision to distinguish glass breakage from other events like bouncing balls, which produce lower frequency vibrations.
Solution Approach 2:
The patent replaces the conventional mechanical accelerometer approach with a piezoelectric sensor system that specifically detects high-frequency vibrations. This substitution enables the system to focus on the characteristic high-frequency signature of glass breakage rather than general vibrations, improving both precision and reliability.
2Reliability
If continuous monitoring is performed to detect vibrations, then detection reliability improves, but power consumption increases
Solution Approach 1:
The patent implements periodic monitoring instead of continuous monitoring. The system activates the vibration detector and signal processor only when needed to assess potential breakage events, rather than continuously analyzing vibrations. This periodic operation maintains detection reliability for breakage events while significantly reducing power consumption during idle periods.
Solution Approach 2:
The patent extracts and analyzes only the high-frequency vibration component above 20 kHz rather than processing all vibration data. This extraction approach reduces the computational load on the signal processor and allows for more efficient power management, as the system can quickly identify genuine breakage events without continuous heavy processing.
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 provides a reliable and power-efficient method to detect shattered windows, reducing false alarms and improving detection accuracy by utilizing high-frequency vibrations and proximity detection, enabling timely alarm signals and energy conservation.
Implementation Method 1
The vibration detector comprises a piezoelectric sensor
Implementation Method 2
The vibration detector comprises an accelerometer
Implementation Method 3
The sensor controller is configured to detect that the windowpane is broken based on filtering out vibrations of a frequency lower than a threshold frequency
Data Source
Figure 1~2
AI summary
It is provided a sensor device comprising: a vibration detector configured to be provided in contact with a windowpane of a window; a sensor controller; and a cable between the vibration detector and the sensor controller; wherein the vibration detector comprises a piezoelectric sensor that is configured to wake up the sensor controller when a vibration is detected by the piezoelectric sensor.