Sensor Window Optical Structures for Privacy-Preserving Motion Detection
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Solution Overview
Problem
Passive infrared (PIR) sensors in lighting systems have low resolution, requiring specific designs for each application, leading to gaps or overlapping in detection areas, which reduces sensitivity and is costly, and raises privacy concerns when used in security cameras.
Innovation Solution
A high-resolution camera with a near-sighted lens system and a light transmissive sensor window featuring optical structures is used for motion detection, ensuring privacy by focusing on a close range and scrambling images, allowing for precise movement sensing without face recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution camera is used for motion detection, then measurement precision and detection range are improved, but privacy concerns worsen due to potential face recognition capabilities
Solution Approach 1:
The patent applies local quality by implementing different optical properties in different regions of the sensor window. The first region has a first optical property that allows motion detection, while the second region has a second optical property that prevents face recognition. This spatial differentiation of optical characteristics enables the system to simultaneously achieve high measurement precision for motion detection while protecting privacy by blocking facial feature recognition in specific areas.
2Object-affected harmful factors
If traditional PIR sensors are used, then privacy is protected, but measurement precision and detection sensitivity deteriorate due to low resolution
Solution Approach 1:
The patent segments the sensor window into multiple regions with different optical properties. By dividing the window into a first region and a second region, each with tailored optical characteristics, the system achieves both privacy protection and high-resolution motion detection. The segmentation allows different parts of the sensor to serve different functions simultaneously.
Solution Approach 2:
The patent changes optical parameters across different regions of the sensor window. By varying the optical properties (such as transparency, refraction index, or optical density) between the first and second regions, the system optimizes each region for its specific function - one for detection precision and another for privacy protection.
3Reliability
If PIR sensors are designed for specific applications, then detection sensitivity is improved, but device complexity and cost increase due to requiring different designs for each application
Solution Approach 1:
The patent implements universality by creating a single sensor unit that can serve multiple detection applications simultaneously. The sensor window with its multiple regions of different optical properties enables the same sensor to handle various detection scenarios (different distances, angles, and target types) without requiring redesign. This multi-functional design reduces device complexity while maintaining high detection sensitivity across diverse applications.
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 cost-effective, high-resolution motion detection system with a larger detection range, capable of counting people and estimating activity, while maintaining privacy and avoiding face recognition, at a cost comparable to traditional PIR sensors.
Implementation Method 1
the lens system is configured to provide a nearsighted (2D) sensor array
Implementation Method 2
a light transmissive sensor window comprising optical structures that scrambles the image
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
The invention provides a sensor unit (100) comprising a sensor array (120) having at least 100x100 sensor pixels (125), a lens system (200), and a light transmissive sensor window (300) comprising optical structures (320), wherein the light transmissive sensor window (300) is configured at a window distance (d) from said sensor array (120), wherein the lens system (200) is configured between the sensor array (120) and said sensor window (300), and wherein an object plane (OP) and an image plane (IP) defined by said lens system (200) and sensor array (120) have an object-image plane distance (d1) selected from the range of 0.1*d – 2*d, wherein the optical structures (320) are configured in a pattern, wherein the optical structures (320) have one or more dimensions selected from length (L), width (W) and diameter (D) selected from the range of 50 µm – 20 mm, and wherein neighboring optical structures (320) shortest distances (d2) selected from the range of 0-50 mm.