Smart-lock Occupancy Detection Using LDR and PIR Sensors
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Solution Overview
Problem
Conventional smart-lock systems fail to reliably indicate room occupancy status when users forget to lock doors, compromising privacy, as they rely on mechanical displays that require the latch to be engaged, leading to inaccuracies if the latch is not applied.
Innovation Solution
The smart-lock system incorporates Light Dependent Resistor (LDR) and Passive Infrared (PIR) sensors on both sides to detect occupancy and luminance, enabling automatic locking and unlocking based on presence detection, with displays on both sides to show occupancy and lock status, and integration with smart devices for enhanced functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical display is used to indicate room occupancy status, then the display structure is simple, but the occupancy detection accuracy deteriorates when the latch is not engaged
Solution Approach 1:
The patent replaces the mechanical latch-based occupancy detection system with an electronic sensor system. LDR sensors detect light changes when the door is opened, and PIR sensors detect infrared radiation from human presence, enabling accurate occupancy detection without relying on the mechanical latch being engaged. This substitution resolves the contradiction by maintaining simple display structure while achieving reliable occupancy detection independent of latch status.
2Measurement precision
If automatic occupancy detection is implemented using sensors, then the occupancy detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The smart-lock system integrates multiple functions into a single device: the LDR and PIR sensors serve both occupancy detection and automatic locking/unlocking functions, while the display system communicates both lock status and occupancy status. This multi-functionality approach reduces overall system complexity despite incorporating sophisticated sensors, as one device performs multiple roles rather than requiring separate systems for each function.
Solution Approach 2:
The patent combines the occupancy detection sensors, locking mechanism, and display system into an integrated smart-lock unit. The LDR sensor on the exterior side and PIR sensor on the interior side work together with the lock actuator and display to provide unified occupancy-based control. This merging of components into a single integrated system manages complexity by consolidating multiple functions into one coordinated device rather than distributing them across separate systems.
3Reliability
If the smart-lock automatically locks when occupancy is detected, then the privacy protection is improved, but the ease of operation deteriorates due to automatic control
Solution Approach 1:
The smart-lock system performs automatic locking and unlocking based on sensor detection of occupancy status without requiring manual user intervention. When the PIR sensor detects human presence inside the room, the system automatically engages the lock; when occupancy ends, it automatically unlocks. This self-service approach improves privacy protection reliability while maintaining ease of operation, as the system handles the locking task autonomously based on objective sensor data rather than relying on user memory or manual action.
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
Ensures accurate and automatic detection of room occupancy, maintaining privacy by locking doors when occupied and unlocking when vacant, while providing users with clear visual and audible feedback on lock status and occupancy, integrating with smart devices for enhanced control and convenience.
Implementation Method 1
The exterior LDR sensor can be used to measure the luminance or the level of brightness of the area surrounding the exterior side of the smart-lock
Implementation Method 2
The interior PIR sensor can be used by the smart-lock to detect the presence of any user inside the room
Data Source
AI summary
A smart-lock system and a method of operating the system is disclosed. The system comprises a smart-lock on a door of a room. The door comprises a first and a second side. The first side of the door lies on the interior side of the room and the second side of the door lies on the exterior side of the room. At least one sensor is disposed on the first side of the door to detect the presence of any user on the interior side of the room and at least one sensor is disposed on the second side of the door to detect the presence of any user at the exterior side of the room. The smart-lock is configured to lock the room when the room is occupied.