Single-Element Door Detector Using Impedance Shift
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Solution Overview
Problem
Commercially available door/window opening detectors require two elements, increasing complexity and cost, necessitating a single-element solution for detection.
Innovation Solution
A single-element door/window opening detector utilizing an antenna with multiple impedance ranges and a proximity indication generator to detect changes in impedance, allowing for the generation of an alarm indication when the antenna is not in proximity to the door/window, powered by a high frequency oscillator and featuring a high-frequency bridge, amplifier, and analog-to-digital converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-element detector system (fixed sensor element on frame and fixed magnetic element on door/window) is used, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the sensor element and magnetic element into a single integrated detector unit mounted on the door or window. The detector includes a magnetically sensitive element that directly senses the magnetic field generated by a magnet in the frame, eliminating the need for separate fixed sensor and magnetic elements. This merging reduces system complexity while maintaining detection functionality through the integrated design of the detector housing that contains both sensing and magnetic components in one unit.
Solution Approach 2:
The single-element detector serves multiple functions: it generates a magnetic field through its internal magnet, senses the magnetic field strength through its magnetically sensitive element, processes the signal through amplifier and comparator circuits, and triggers alarm indications. This multi-functional integration replaces the need for separate sensor and magnetic elements, reducing system complexity while maintaining reliable detection capability.
2Measurement precision
If two-element detector system is used, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple components into a single detector unit including the magnet, magnetically sensitive element, amplifier, comparator, and alarm indication generator. This consolidation reduces the number of parts that need to be manufactured and assembled, lowering manufacturing costs while maintaining detection accuracy through the integrated design.
Solution Approach 2:
The detector is designed to be self-contained with all necessary components (magnet, sensing element, signal processing circuits, and alarm indication) integrated into one unit. This self-service design eliminates the need for complex installation and calibration procedures required by two-element systems, reducing both manufacturing and installation costs while maintaining detection precision.
3Device complexity
If single-element detector is used, then device complexity is reduced, but detection reliability may deteriorate
Solution Approach 1:
The single-element detector achieves reliable detection by integrating multiple functions into one unit: magnetic field generation, magnetic field sensing, signal amplification, threshold comparison, and alarm indication. This multi-functional integration ensures that all detection components work together in a coordinated manner, maintaining reliability while reducing system complexity.
Solution Approach 2:
The detector incorporates feedback mechanisms through the amplifier and comparator circuits that continuously monitor the magnetic field strength and compare it against predetermined thresholds. This feedback system ensures reliable detection by automatically adjusting the signal processing to maintain accurate detection despite variations in environmental conditions or component tolerances.
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 cost-effective and simplified detection of door/window opening with reduced complexity, capable of communicating alarm indications to a premises monitoring system.
Implementation Method 1
the at least one antenna having a first impedance within the first range of impedance when in proximity to an article having a given dielectric constant and having a second impedance within the second range of impedance and not within the first range of impedance when not in proximity to the article having the given dielectric constant
Implementation Method 2
a high frequency oscillator operable for generating a high frequency oscillating electromagnetic signal for excitation of the at least one antenna
Data Source
AI summary
An article proximity indicator including at least one antenna having at least first and second ranges of impedance, the second range of impedance being at least partially different from the first range of impedance, the at least one antenna having a first impedance within the first range of impedance when in proximity to an article having a given dielectric constant and having a second impedance within the second range of impedance and not within the first range of impedance when not in proximity to the article having the given dielectric constant, and a proximity indication generator operable, in response to receiving an indication that the impedance of the at least one antenna has changed from being within the first range of impedance to being within the second range of impedance, for generating an indication indicating that the at least one antenna is not in proximity to the article.