TOF Sensor Position Acquisition for Transmissive Objects
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Solution Overview
Problem
Existing technologies face challenges in acquiring accurate position information for objects in diverse environments, particularly in scenarios with transmissive objects, as they struggle to detect and differentiate between objects based on their transmittance and reflectance.
Innovation Solution
A position information acquisition device and method utilizing a TOF sensor that detects temporal changes in photon degrees from pulsed irradiation light, identifying local maximum points to determine distances to objects, regardless of their transmittance, and outputs this information for use in head-mounted displays and various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LiDAR technologies (dToF or iToF) are used to acquire position information, then distance measurement capability is provided, but accurate detection of transmissive objects and differentiation between overlapping objects is difficult
Solution Approach 1:
The patent applies periodic pulsed irradiation light to the object and performs repeated measurements at different time points. By irradiating with pulsed light and detecting reflected light intensity changes over time, the system identifies local maximum points in the temporal intensity curve, which correspond to distances of different objects (including transmissive objects). This periodic measurement approach enables differentiation between overlapping objects that conventional single-point LiDAR cannot distinguish.
Solution Approach 2:
The patent dynamically adjusts measurement timing and analyzes temporal changes in reflected light intensity. Instead of using fixed measurement intervals, the system performs measurements at multiple time points during the flight time of light and identifies local maximum points in the intensity temporal change. This dynamic measurement strategy allows the system to adapt to varying object positions and properties, particularly enabling detection of transmissive objects that have different reflectance characteristics.
2Adaptability or versatility
If a single measurement point is used in conventional LiDAR, then device complexity is reduced, but the ability to detect multiple objects at different positions is lost
Solution Approach 1:
The patent uses a single measurement point (single pixel or detector) but performs periodic measurements at multiple time points corresponding to different light flight times. By analyzing the temporal change in reflected light intensity at this single point, the system can identify local maximum points that indicate the presence of objects at different distances. This approach achieves multi-object detection capability without requiring multiple spatially separated detectors, thus maintaining relatively simple device structure.
Solution Approach 2:
The patent transitions from spatial dimension to temporal dimension for object differentiation. Instead of using multiple detectors positioned at different spatial locations, the system uses a single detector and distinguishes objects by their temporal characteristics (time of flight). The temporal intensity curve shows local maximum points at different time points, each corresponding to a different object distance. This dimensional transformation enables multi-object detection while keeping the device structure simple.
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
Enables accurate and efficient acquisition of position information in diverse environments, including transmissive objects, enhancing the range of uses and improving user safety and experience in VR and AR applications.
Implementation Method 1
LiDAR includes dToF (direct Time of Flight) that determines a distance on the basis of a time difference between the irradiation with pulsed light and the observation of the reflected light
Implementation Method 2
a degree observer configured to acquire a temporal change in a degree of photons resulting from a pulsed irradiation light being reflected by an object
Data Source
AI summary
Pulsed light emitted from a light emitter of a TOF sensor at an intensity is divided into light that is reflected by an object having transmissivity and reaches a light receiver at an intensity and light that passes through the object and reaches an object at an intensity. The latter is reflected by the object at an intensity, partly passing through the object to reach the light receiver at an intensity. A local maximum point is detected in a change in a degree of photons observed by the light receiver, to acquire both distances to the object and the object.