Electronic Lockbox Single-Sensor Detection of Magnetic Key Fob Presence
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Solution Overview
Problem
Conventional electronic lockboxes for real estate do not effectively detect the presence or absence of a building key within the secure compartment, leading to issues such as forgotten or stolen keys, and often require multiple sensors to determine the status of the key compartment and the presence of a key fob.
Innovation Solution
An electronic lockbox with a single magnetic sensor that can detect multiple magnetic field magnitude levels to determine the position of a movable key bin and the presence of a removable key fob, using a Hall effect sensor and analog-to-digital converter to differentiate between open, closed, and closed-with-key-fob states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sensors are used to detect key compartment status and key fob presence, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The magnetic sensor is designed to perform multiple detection functions: it detects both the position of the key compartment (open/closed) and the presence of the key fob within the compartment. By making the sensor universal, the system achieves reliable detection of multiple parameters without increasing sensor quantity, thus resolving the contradiction between detection reliability and device complexity
Solution Approach 2:
The patent combines the key compartment position detection and key fob presence detection into a single magnetic sensor system. The sensor merges multiple detection capabilities into one component, eliminating the need for separate sensors and reducing overall system complexity while maintaining comprehensive monitoring reliability
2Device complexity
If a single sensor detects multiple magnetic field levels, then device complexity is reduced, but measurement precision requirements increase
Solution Approach 1:
The system utilizes different magnetic field magnitude levels as distinct parameters to represent different states: a first magnitude level indicates the key compartment is closed, a second level indicates it is open, and a third level indicates the key fob is present. By changing and monitoring magnetic field parameters, the single sensor can precisely differentiate between multiple states without requiring additional sensors
Solution Approach 2:
The magnetic field acts as an intermediary that carries information about both key compartment position and key fob presence. The magnetic sensor detects variations in this intermediary field, allowing indirect but precise measurement of multiple conditions through a single detection point, thereby reducing complexity while maintaining measurement precision
3Reliability
If magnetic sensor detects key fob presence in closed compartment, then key loss prevention is improved, but false detection risk increases
Solution Approach 1:
The system continuously monitors magnetic field magnitude levels and compares them against predetermined thresholds to determine key compartment and key fob status. This feedback mechanism allows the system to dynamically adjust its detection logic, confirming readings against expected patterns and reducing the likelihood of false detections while maintaining reliable key loss prevention
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 reliable detection of key compartment status and key fob presence, reducing the risk of key loss and ensuring secure key management with a single sensor system.
Implementation Method 1
A Hall effect sensor is a preferred type of magnetic sensor for this purpose
Data Source
AI summary
An electronic lockbox with a single sensor that can detect both the position of a key compartment component (or a movable key bin) and the presence of a removable key fob (attached to a building key). The key compartment includes a first magnet and the removable key fob includes a second magnet. The single sensor can detect the presence of neither magnet, the first magnet alone, or both the first and second magnet together. If neither magnet is detected, then the key compartment (movable bin) is open. If only the first magnet is detected, then the key compartment (movable bin) has been closed without the removable key fob. If both the first and second magnets are detected, then the key compartment (movable bin) is closed with the removable key fob inside the movable bin.