3D Time-of-Flight Camera Internal Reference Target for Continuous Functional Testing
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Solution Overview
Problem
Conventional 3D time-of-flight cameras face challenges in maintaining reliability and availability due to the inability to perform functional tests without interrupting the measurement process, especially in safety-critical applications where continuous operation is required.
Innovation Solution
A 3D time-of-flight camera that uses multiple modulation frequencies to enable simultaneous measurement and functional testing, with an internal reference target within the camera housing to allow continuous operation and self-monitoring of detection capability, ensuring the camera's reliability and safety standards are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If functional tests are performed to monitor detection capability, then reliability is improved, but measurement operation must be interrupted reducing availability
Solution Approach 1:
The patent implements periodic functional tests at specific time points during continuous measurement operations. The system performs time-of-flight measurements continuously and incorporates functional tests at defined intervals without completely interrupting the measurement process, allowing the system to maintain both reliability monitoring and measurement availability through structured periodic testing
Solution Approach 2:
The patent performs functional tests at predetermined time points before critical failures can occur. By scheduling tests in advance and preparing reference values beforehand, the system can quickly validate detection capability without lengthy interruption, thus maintaining high measurement availability while ensuring reliability
2Measurement precision
If multiple frequencies are used for modulation, then measurement accuracy and unambiguous range are improved, but device complexity increases
Solution Approach 1:
The patent employs multiple modulation frequencies simultaneously to achieve multiple functions: extending the unambiguous measurement range, improving distance measurement accuracy, and enabling differentiation of multiple targets at different distances. This multi-frequency approach allows a single measurement system to perform several measurement tasks that would otherwise require separate systems
Solution Approach 2:
The patent changes the modulation frequency parameter to optimize measurement performance. By using at least two different modulation frequencies, the system can determine phase shifts more accurately and calculate distances with higher precision while maintaining a relatively simple overall device structure through parameter optimization rather than structural complexity
Data Source
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AI summary
A 3D time-of-flight camera (10) for capturing three-dimensional image data from a detection area (18) is specified, comprising an illumination unit (12) for emitting transmitted light (14) modulated in at least two frequencies into the detection area (18), an image sensor (24) with a plurality of pixels (24a) for generating received signals from transmitted light (20) reflected in the detection area (18), a plurality of evaluation circuits (26) assigned to the pixels (24a) for determining at least one distance per pixel (24a) from the received signals by means of a time-of-flight method based on the at least two frequencies, and an internal reference target (32, 36, 38, 40) which directs a part of the transmitted light (14) or test light (42) within the 3D time-of-flight camera (10) onto the image sensor (24).The 3D time-of-flight camera (10) is safely designed and has an evaluation unit (28) which compares a measurement quantity of the reference target (32, 36, 38, 40) determined by the evaluation circuits (26) with a reference measurement quantity for a functional test.