TOF 3D Measuring Device Adjusting Light Emission for Accuracy
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Solution Overview
Problem
The Time of Flight (TOF) method for three-dimensional measurement is affected by unwanted reflected light from the surrounding environment, leading to reduced ranging accuracy, as it includes direct and scattered light components, which existing methods fail to eliminate effectively.
Innovation Solution
A three-dimensional measuring device with a light source unit that adjusts light emission for different irradiation regions based on a region light amount signal, allowing the image processing unit to isolate and remove unwanted reflected light components, ensuring accurate measurement by using only direct reflected light from the target object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the TOF method is used for three-dimensional measurement, then measurement coverage and speed are improved, but ranging accuracy is reduced due to unwanted reflected light from the surrounding environment
Solution Approach 1:
The patent divides the measurement process into multiple phases: a first measurement phase using TOF method for rapid measurement, and a second measurement phase using structured light for accurate measurement. This segmentation allows the system to achieve both high measurement speed and high accuracy by using appropriate methods for different purposes.
Solution Approach 2:
The patent introduces an intermediary measurement phase using structured light projection and recognition as a mediator between the rapid TOF measurement and the final accurate measurement. This intermediary process allows the system to compensate for the inaccuracies introduced by unwanted reflected light in the TOF method.
2Area of stationary object
If light is emitted with uniform luminous intensity distribution, then measurement coverage is improved, but measurement accuracy is reduced due to scattered light from the surrounding environment
Solution Approach 1:
The patent employs different light emission patterns for different measurement phases: uniform luminous intensity distribution in the first phase for broad coverage, and non-uniform patterns in the second phase for localized accurate measurement. This local quality approach allows the system to optimize both coverage and accuracy at different stages.
Solution Approach 2:
The patent uses periodic alternating measurement phases where structured light is projected at specific intervals during the second measurement phase. This periodic action allows the system to systematically eliminate the influence of scattered light by comparing measurements taken with and without structured light projection.
3Illumination intensity
If the amount of light emitted to all irradiation regions is increased, then signal strength is improved, but measurement accuracy is reduced due to increased scattered light from the surrounding environment
Solution Approach 1:
The patent applies partial action by selectively increasing light emission intensity only in specific irradiation regions during the second measurement phase, rather than uniformly increasing intensity across all regions. This allows sufficient signal strength where needed while minimizing scattered light in other regions.
Solution Approach 2:
The patent changes the light emission parameters (intensity, distribution pattern) dynamically between different measurement phases and for different irradiation regions. By adjusting these parameters, the system achieves optimal signal strength while controlling scattered light contributions to maintain measurement accuracy.
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 accurate three-dimensional measurement by eliminating the influence of unwanted reflected light, thereby improving the ranging accuracy regardless of the surrounding environment, and reducing measurement errors caused by scattered light.
Implementation Method 1
the time of flight (TOF) from transmission of light pulses to reception of the pulses reflected from an object depends on the distance
Implementation Method 2
a light receiving unit configured to be exposed to light from a region including a target object at timing indicated by an exposure control signal and to produce three-dimensional information from a total exposure amount
Data Source
AI summary
In a ranging system using a TOF method, an unwanted reflected light component included in reflected light is reduced or removed. A light source unit emits light at the timing indicated by a light emission control signal and can adjust for each of at least two irradiation regions the amount of light to be emitted. A light receiving unit is exposed to light from a region including a target object and produces three-dimensional information from the total exposure amount. An image processing unit generates a distance image based on the three-dimensional information received from the light receiving unit. The light source unit emits light according to a radiation pattern indicated by a region light amount signal. The radiation pattern is setting of the amount of light to be emitted to each irradiation region.