ToF Camera Temperature Error Correction via Reference Light
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Solution Overview
Problem
Time of flight (ToF) camera systems face significant challenges in accurately correcting temperature-related measurement errors, which affect the precision of depth image generation due to temperature fluctuations influencing both the illumination and sensor units, as well as set exposure times and frame rates.
Innovation Solution
A ToF camera system and method that incorporate temperature measuring units for the sensor and illumination units, along with exposure time and frame rate measurements, to correct temperature-related errors by weighting differences between current and reference temperatures, exposure times, and frame rates using specific correction coefficients, thereby stabilizing the measurement process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature-related measurement errors are corrected using conventional methods, then measurement precision is improved, but device complexity increases due to multiple temperature measuring units and correction calculations
Solution Approach 1:
The patent extracts the temperature measurement function from separate dedicated temperature sensors and integrates it into the existing pixel structure. The same pixels that capture reflected light are used to detect reference light, which carries temperature-induced phase shift information. This eliminates the need for separate temperature measuring units while still enabling temperature error correction.
Solution Approach 2:
The patent makes the pixel structure multi-functional by using it for both depth measurement (capturing reflected light from objects) and temperature compensation (capturing reference light). The reference light path allows pixels to serve dual purposes: measuring object distance and detecting temperature-related phase shifts, thereby reducing overall system complexity.
2Measurement precision
If multiple temperature measuring units are added to correct errors, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent removes the need for separate temperature sensors and their associated mounting, calibration, and integration processes. By using existing pixels for temperature detection through reference light, the manufacturing process is simplified and tolerance requirements are reduced.
Solution Approach 2:
The system uses its own existing components (pixels and reference light path) to perform temperature measurement and compensation, rather than requiring externally manufactured temperature sensors. This self-service approach reduces the number of manufactured parts and lowers overall manufacturing precision requirements.
3Measurement precision
If complex correction calculations are performed, then measurement precision is improved, but processing time increases
Solution Approach 1:
The patent performs temperature compensation in real-time by continuously capturing reference light and calculating phase shifts during normal operation. The correction is integrated into the measurement process itself rather than being a separate post-processing step, enabling timely correction without significant processing delays.
Solution Approach 2:
The system uses feedback from the reference light measurements to continuously adjust and correct depth measurements. The phase shift information from reference light provides real-time temperature compensation data that is fed back into the measurement process, enabling dynamic correction without extensive processing time.
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 efficient and stable correction of temperature-related measurement errors in ToF camera systems, reducing processing complexity and improving the accuracy of depth image generation by directly addressing current temperature and operational parameter influences.
Implementation Method 1
The aim of a ToF measurement is therefore to measure this time and thus calculate the distance to the object
Implementation Method 2
The emitted light is reflected by the objects in the environment, returns to the camera, and is detected by a sensor
Implementation Method 3
Temperature fluctuations change the signal propagation times of the light and shutter pulses, which leads to a distance-independent error
Data Source
AI summary
A time of flight, ToF, camera system for measuring depth images of an environment is disclosed, wherein the ToF camera system includes an illumination unit comprising a light source for emitting modulated light signals for illuminating objects of the environment and a sensor unit comprising an image sensor for acquiring light signals reflected from the objects. A processing unit for generating the depth images based on the acquired reflected light signals and a correction unit for correcting temperature-related measurement errors of the generated depth images is included.