Passive Infrared Sensor With Asymmetric Lens for Direction Detection
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Solution Overview
Problem
Traditional passive infrared sensors struggle to determine the direction of travel of individuals passing through their field of view, making it difficult to accurately count the number of people entering or exiting a given area.
Innovation Solution
A passive infrared sensor device equipped with a lens featuring an asymmetric obstruction that focuses infrared radiation onto the sensor, combined with a control circuit analyzing sensor signals using threshold values and machine learning algorithms to detect and determine the direction of passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional passive infrared sensor is used to detect individuals passing through an area, then the sensor can detect the presence of individuals, but it cannot determine the direction of travel of individuals
Solution Approach 1:
The patent applies asymmetry by introducing an asymmetric obstruction pattern on the lens that is not symmetric with respect to the optical axis. This asymmetric pattern causes the sensor to detect different signal characteristics for individuals moving in different directions, enabling direction detection without adding complex mechanical moving parts or multiple sensors. The asymmetric obstruction modifies the infrared radiation distribution in a way that preserves direction information while maintaining a simple single-sensor structure.
2Measurement precision
If multiple sensors are used to determine direction of travel, then direction detection accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent segments the lens aperture into multiple regions with different obstruction patterns, creating distinct optical paths for different directions of travel. By dividing the lens into segments with asymmetric obstructions, the system can distinguish between individuals moving in different directions using a single sensor, avoiding the need for multiple sensors while maintaining direction detection accuracy.
Solution Approach 2:
The patent applies local quality by creating different obstruction patterns at different locations on the lens. Each region of the lens has a specific obstruction configuration that is optimized for detecting individuals moving in particular directions. This local differentiation allows the single sensor to capture directional information through spatial variation in the obstruction pattern, eliminating the need for multiple sensors.
3Measurement precision
If complex signal processing algorithms are used to determine direction, then direction detection capability improves, but processing time and computational resources increase
Solution Approach 1:
The patent substitutes complex computational direction detection methods with an optical-mechanical solution using asymmetric obstructions on the lens. Instead of relying solely on complex signal processing algorithms to determine direction, the asymmetric physical structure of the lens encodes directional information directly into the optical signal pattern, enabling faster and simpler processing by reducing the computational complexity required to extract direction data.
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
Effectively detects the passage and direction of individuals, enabling accurate counting of people entering or exiting an area with low power consumption and improved reliability.
Implementation Method 1
The passive infrared sensor can sense infrared radiation emitted by individuals as they pass within the field of view of the passive infrared sensor
Implementation Method 2
a lens that focuses infrared radiation from individuals onto the passive infrared sensor
Implementation Method 3
The asymmetric obstruction occludes a portion of the lens, while leaving another portion of the lens unobstructed
Data Source
AI summary
A sensor device includes a passive infrared sensor, a control circuit, and a lens that directs infrared radiation onto the passive infrared sensor. The lens includes an obstruction that asymmetrically blocks transmission of infrared radiation through the lens. The control circuit is configured to determine the direction of crossing of individuals passing in front of the sensor device based on sensor signals from the passive infrared sensor.