Ranging Apparatus Merging ToF and Phase Difference Systems
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Solution Overview
Problem
The accuracy of ranging in Time of Flight (ToF) systems is compromised by the reflectance of objects, making it difficult to achieve precise distance measurements, even with direct and indirect ToF systems.
Innovation Solution
A ranging apparatus that combines a ToF system and a phase difference system, utilizing a light-emitting unit, a plurality of pixels, a shared microlens, a first ranging unit for time-based distance measurement, and a second ranging unit for phase difference-based distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a ToF system is used for distance measurement, then ranging speed is improved, but ranging accuracy deteriorates due to dependence on object reflectance
Solution Approach 1:
The patent combines a ToF system and a phase difference system into a single ranging apparatus. The ToF system provides fast ranging speed while the phase difference system compensates for accuracy limitations caused by low object reflectance. By merging these two systems, the apparatus achieves both high speed and high accuracy ranging performance.
Solution Approach 2:
The imaging element is designed to perform multiple functions: it serves as both a light receiver for the ToF system and a pixel array for the phase difference system. This multi-functional design allows the same hardware component to support both ranging methods, enabling the apparatus to switch between or combine them based on measurement conditions.
2Device complexity
If only a ToF system is used, then device complexity is reduced, but ranging accuracy deteriorates under varying reflectance conditions
Solution Approach 1:
The patent integrates the ToF system and phase difference system within a unified apparatus structure. By merging these systems and sharing common components like the imaging element and light-emitting unit, the patent reduces the overall complexity increase that would result from completely separate systems while maintaining the accuracy benefits of dual-system operation.
3Measurement precision
If a phase difference system is used, then ranging accuracy is improved for low reflectance objects, but device complexity increases
Solution Approach 1:
The imaging element serves dual purposes as both a light receiver for ToF measurements and a pixel array for phase difference detection. This multi-functionality allows the phase difference system to be implemented without requiring completely separate hardware, thereby limiting the increase in device complexity while achieving improved ranging accuracy.
Solution Approach 2:
The patent merges the phase difference system with the ToF system by sharing common components such as the imaging element and control circuits. This integration approach reduces the overall device complexity compared to implementing separate independent systems, while still providing the accuracy improvements needed for low reflectance objects.
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 combination enhances ranging accuracy by leveraging both time-of-flight and phase difference measurements, improving the reliability of distance calculations regardless of object reflectance.
Implementation Method 1
a first ranging unit configured to acquire a distance to the object, based on a time it takes to receive reflected light of the light radiated by the light-emitting unit
Implementation Method 2
a microlens that is arranged on the plurality of pixels and that is shared by the plurality of pixels
Data Source
AI summary
A ranging apparatus includes a light-emitting unit configured to irradiate an object with light; a plurality of pixels; a microlens that is arranged on the plurality of pixels and that is shared by the plurality of pixels; a first ranging unit configured to acquire a distance to the object, based on a time it takes to receive reflected light of the light radiated by the light-emitting unit; and a second ranging unit configured to acquire a distance to the object, based on a difference among respective outputs of the plurality of pixels having received the reflected light.