Depth Image Sensor Airborne Particle Detection
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Solution Overview
Problem
Current depth image cameras struggle to accurately detect airborne particles such as dust, fog, rain, and snow due to interference from environmental features, which complicates the measurement of modulated light used in Time of Flight (ToF) and structured light sensing.
Innovation Solution
The method involves obtaining a reference measurement of the environment using modulated light in a first time interval, which is then used to disregard background features, allowing for the detection of airborne particles in a subsequent measurement interval by adjusting the emission of modulated light to exclude the background, thereby isolating the measurement range to detect particles between the sensor and features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If depth image cameras use modulated light measurement to detect airborne particles, then particle detection capability is improved, but environmental features cause interference and reduce measurement precision
Solution Approach 1:
The patent segments the measurement process into two distinct phases: a reference measurement phase to capture environmental features, and a particle detection phase to measure airborne particles. By separating these measurements in time and processing them independently, the system can subtract the environmental background from the particle measurement, thereby improving particle detection precision while eliminating environmental interference.
2Measurement precision
If reference measurement is used to disregard environmental features, then particle detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent performs a preliminary reference measurement of the environmental features before conducting the actual particle detection. This preliminary action captures the background environment (walls, furniture, static objects) so that it can be subtracted from subsequent measurements. This approach improves particle detection accuracy while keeping the processing relatively simple, as it only requires storing and subtracting the reference data.
3Area of stationary object
If modulated light is emitted continuously for measurement, then detection coverage is improved, but energy consumption increases
Solution Approach 1:
The patent employs periodic action by emitting modulated light in specific time intervals rather than continuously. The system performs measurements during defined time windows (such as during specific phases of the modulation cycle) and uses reference measurements taken at different times. This periodic measurement approach maintains adequate detection coverage while significantly reducing energy consumption compared to continuous operation.
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
This approach enables precise detection and characterization of airborne particles by generating a signal indicative of their properties, including location, composition, and density, without requiring significant changes to existing ToF or structured light sensor technology.
Implementation Method 1
ToF cameras are based on a measurement of a delay between the emission of an optical infra-red (IR) signal, which is then reflected by an object, and the reception of the optical signal at a photon mixing device (PMD) imager. The measured delay is proportional to the distance of the object.
Implementation Method 2
The reference measurement is based on a measurement of modulated light in a first time interval. The modulated light is reflected by features of the environment of the depth image sensor module.
Data Source
AI summary
Examples relate to a method, an apparatus and a computer program for detecting a presence of airborne particles. A reference measurement of an environment of a depth image sensor module is obtained. The reference measurement is based on a measurement of modulated light in a first time interval. The modulated light is reflected by features of the environment of the depth image sensor module. A subsequent measurement of modulated light is obtained in a second time interval. The presence of the airborne particles is detected based on the subsequent measurement of the modulated light, by using the reference measurement performed in the first time interval to disregard all or part of the features of the environment of the depth image sensor module. A signal indicative of one or more properties of the detected airborne particles is generated based on the detected presence of the airborne particles.