Range Finding Apparatus with Dual-Sensitivity Pixels for Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time-of-Flight range-finding accuracy is limited by the measurement accuracy of the time difference between light emission and reflection, and existing methods do not effectively account for the differences in sensitivity between light-receiving elements, leading to noise interference and reduced accuracy.
Innovation Solution
A range finding apparatus with a light-receiving device featuring pixels of different sensitivities, where high-sensitivity and low-sensitivity pixels are arranged two-dimensionally, and the measurement resolution for the low-sensitivity pixels is lower than for the high-sensitivity pixels, allowing for appropriate processing to handle sensitivity differences and reduce noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-sensitivity pixels are used for all light-receiving elements, then the ability to detect weak reflected light is improved, but noise light interference increases and measurement accuracy deteriorates
Solution Approach 1:
The patent applies local quality by assigning different sensitivity characteristics to different pixels within the light-receiving device. Specifically, first pixels are configured with first sensitivity characteristics while second pixels have second sensitivity characteristics that differ from the first. This allows each pixel type to be optimized for specific measurement conditions, with less-sensitive pixels used when noise light is present and highly-sensitive pixels used for weak reflected light detection, thereby resolving the contradiction between detecting weak signals and rejecting noise.
2Measurement precision
If measurement resolution is increased for all pixels, then time difference measurement accuracy is improved, but processing complexity and data volume increase
Solution Approach 1:
The patent implements local quality by applying different measurement resolutions to different pixel types. The measuring unit measures time periods for first pixels with a first measurement resolution and for second pixels with a second measurement resolution that is lower than the first. This differentiated approach reduces overall processing complexity and data volume while maintaining high measurement accuracy where needed, as less-sensitive pixels do not require the same level of measurement precision as highly-sensitive pixels.
3Adaptability or versatility
If only single-sensitivity pixels are used, then device structure is simplified, but dynamic range and adaptability to different lighting conditions are reduced
Solution Approach 1:
The patent resolves this contradiction by configuring different pixels with different sensitivity characteristics within the same light-receiving device. First pixels have first sensitivity characteristics while second pixels have second sensitivity characteristics, enabling the device to handle a wider dynamic range of light intensities. The controller selectively activates appropriate pixel types based on lighting conditions, providing adaptability without requiring completely separate devices for different measurement scenarios.
Solution Approach 2:
The patent applies dynamics by enabling the controller to dynamically select which pixel type to use based on real-time lighting conditions and measurement requirements. The controller can switch between using first pixels and second pixels depending on whether the environment has strong noise light or requires detection of weak reflected light, making the device adaptable to varying operational conditions while maintaining a unified device structure.
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 enhances the accuracy of distance measurement by effectively managing noise and improving the dynamic range of the light-receiving device, leading to more precise range-finding results even in environments with significant noise or at long distances.
Implementation Method 1
Each SPAD generates an avalanche current when a photon is incident, as a result of an avalanche photodiode being operated in Geiger mode
Data Source
AI summary
A range finding apparatus uses a light-receiving device in which a first pixel having a first sensitivity and a second pixel having a second sensitivity that is lower than the first sensitivity are two-dimensionally arranged. The range finding apparatus measures time periods from a predetermined time until times when light is incident on each of the first pixel and the second pixel, and computes distance information for the first pixel and the second pixel based on the measured time periods. The measurement resolution used to measure the time period for the second pixel is lower than a measurement resolution used to measure the time period for the first pixel.