Optical ToF Sensor Timing Correction Under Ambient Light
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Solution Overview
Problem
Existing distance measurement methods using the time-of-flight principle are inaccurate in the presence of ambient light due to changes in light pulse amplitudes and pulse widths, leading to measurement errors.
Innovation Solution
The method and optical sensor correct reception times by determining the intensity of ambient light and performing corrections based on pulse width and intensity, using a control and evaluation unit to calculate effective reception times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-of-flight measurement is performed without ambient light correction, then measurement process is simple, but measurement accuracy deteriorates in presence of ambient light
Solution Approach 1:
The patent applies preliminary action by determining the pulse width of each detected light pulse before performing the basic correction of reception time. The control and evaluation unit measures the pulse width parameter and uses it to calculate the appropriate correction value, ensuring that the correction is prepared in advance based on the actual pulse characteristics rather than applying a fixed correction method.
Solution Approach 2:
The patent implements parameter changes by using the determined pulse width as a variable parameter to adjust the basic correction of reception time. Instead of applying a uniform correction, the system dynamically changes the correction value based on the measured pulse width parameter, allowing the measurement system to adapt to different light pulse conditions and maintain accuracy.
2Measurement precision
If pulse width-dependent correction is applied, then measurement accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent applies self-service by having the control and evaluation unit automatically determine the pulse width of each detected light pulse and autonomously calculate the appropriate correction value based on this measured parameter. The system uses its own measurement capabilities (pulse width detection) to generate the correction data it needs, without requiring external calibration or additional reference measurements.
3Reliability
If ambient light intensity is determined and correction is performed, then measurement reliability improves in ambient light conditions, but processing time increases
Solution Approach 1:
The patent implements periodic action by integrating the ambient light correction process into the regular measurement cycle. The control and evaluation unit periodically determines the ambient light intensity and applies corrections at each measurement interval, making the correction a routine part of the measurement process rather than a separate, time-consuming operation. This ensures consistent reliability while minimizing additional 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 significantly increases measurement accuracy by compensating for the effects of ambient light, ensuring reliable distance measurements even in challenging lighting conditions.
Implementation Method 1
light pulses reflected back from an object in the monitoring area
Implementation Method 2
a receiving unit for detecting light pulses reflected back from an object
Data Source
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AI summary
The invention relates to a method for measuring the distance to an object based on the time-of-flight principle, in which light pulses are emitted into a monitoring area, light pulses reflected back from an object in the monitoring area are detected by a receiving unit, and a distance to the object is determined based on the time of flight of the light pulses, wherein a basic correction of the reception time of the respective light pulse is performed. The method is characterized in that the intensity of ambient light incident on the receiving unit or a photodetector in the vicinity of the receiving unit is detected, and that, depending on the detected intensity of the ambient light, an ambient light correction of the reception times of the detected light pulses is performed. The invention also relates to an optical sensor.