Offset Optical Security Sensor for Door Tamper Resistance
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Solution Overview
Problem
Existing door and window sensors can be easily defeated by intruders, either by holding the sensor in a depressed state with a thin object or by mimicking the magnetic detection with another magnet, allowing unauthorized opening to go undetected.
Innovation Solution
A door sensor system utilizing an optical emitter and receiver with a reflector arrangement, where the optical beam is laterally offset by at least an inch and diverges at an angle of at least two degrees, making it difficult for intruders to intercept or replicate the beam, and incorporating a unique signal that varies between modules or over time to prevent tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pushbutton sensor is used to detect door opening, then the sensor can detect door state changes, but an intruder can defeat it by inserting a thin object to hold the pushbutton in a depressed state
Solution Approach 1:
The patent replaces the mechanical pushbutton sensor with an optical detection system consisting of an optical emitter, optical receiver, and reflector arrangement. This substitution eliminates the vulnerability to mechanical defeat methods while maintaining door state detection capability through optical beam interruption or reflection changes.
Solution Approach 2:
The patent introduces a reflector arrangement as an intermediary element in the optical path. The reflector reflects the optical beam back to the receiver, creating a more complex interaction path that cannot be easily replicated by simple mechanical objects, thereby enhancing security against intruder defeat attempts.
2Reliability
If a magnetic reed switch sensor is used to detect door opening, then the sensor can monitor magnet presence, but an intruder can defeat it by attaching another magnet to interrupt detection
Solution Approach 1:
The patent replaces the magnetic reed switch sensor with an optical detection system. This substitution eliminates the vulnerability to magnetic defeat methods while maintaining door state detection capability through optical beam interruption or reflection changes, which cannot be easily replicated by simple magnets.
Solution Approach 2:
The patent changes the detection parameter from magnetic field presence to optical beam interaction (interruption or reflection). This parameter change makes the system immune to magnetic spoofing attacks while maintaining effective door state monitoring through the optical properties of the door assembly.
3Object-affected harmful factors
If an optical beam is used with a reflector arrangement, then intruder defeat becomes difficult, but the beam path complexity increases
Solution Approach 1:
The patent uses a reflector arrangement that reflects the optical beam back along a different spatial path than the incident beam. This creates a multi-dimensional optical interaction where the beam travels out and back through different geometric paths, making intruder defeat difficult while managing complexity through structured geometric design rather than random complexity.
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 system effectively prevents unauthorized door or window opening detection by intruders, as the offset beam and varying signal make it challenging to intercept or replicate the optical signal, enhancing security and reliability.
Implementation Method 1
The axis of emission diverges in the emission direction from the axis of reception at an angle of at least two degrees
Implementation Method 2
A reflector arrangement includes at least one reflective surface and is mounted in association with the other of the first surface and the second surface. The at least one reflective surface receives at least a portion of the first beam and produces a second beam directed at and received by the optical receiver
Data Source
AI summary
A security sensor apparatus senses movement of an object. The sensor apparatus includes an electronics arrangement having an optical emitter and an optical receiver. The optical receiver has an axis of reception. The optical emitter emits a first beam along an axis of emission in an emission direction. The axis of emission diverges in the emission direction from the axis of reception at an angle of at least two degrees. The electronics arrangement is mounted in association a first surface of the object or a second surface of a structure disposed in opposition to the first surface. A reflector arrangement includes at least one reflective surface and is mounted in association with the other of the first surface and the second surface. The at least one reflective surface receives at least a portion of the first beam and produces a second beam directed at and received by the optical receiver.