Time of Flight Ranging Reflectance Calculation
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Solution Overview
Problem
Traditional ranging systems primarily provide distance measurements but fail to accurately account for target reflectance, which can degrade accuracy and is necessary for certain applications.
Innovation Solution
An electronic device with a ranging light source and reflected light detector calculates target reflectance by determining the intensity of reflected light and distance, using various mathematical formulas involving exponential functions and coefficients to accurately determine reflectance, enabling applications such as autofocus and ink level detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ranging systems only measure distance, then the device complexity is low, but the measurement precision degrades due to unaccounted reflectance variations
Solution Approach 1:
The system measures the intensity of reflected light and uses this feedback to calculate and compensate for target reflectance. By incorporating the reflected light intensity measurement into the distance calculation process, the system dynamically adjusts for reflectance variations, thereby improving measurement precision without requiring complex hardware modifications
Solution Approach 2:
The patent introduces reflected light intensity as an intermediary parameter that mediates between the raw distance measurement and the final corrected distance. This intermediary measurement allows the system to account for reflectance effects through mathematical correction formulas, improving accuracy while maintaining relatively simple device architecture
2Measurement precision
If the system calculates reflectance using multiple mathematical formulas and coefficients, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The system performs preliminary measurements of reflected light intensity and preliminary calculations of reflectance values before final distance determination. By pre-calculating reflectance compensation factors and storing reference coefficients, the system reduces the complexity of real-time calculations while maintaining high measurement precision
Solution Approach 2:
The patent transforms the complex reflectance calculation problem into a series of parameter adjustments. By changing the form of calculation from direct physical modeling to empirical parameter fitting using exponential functions and coefficients, the system achieves high precision reflectance determination while keeping the computational approach manageable
3Adaptability or versatility
If the ranging system provides only distance output, then the ease of operation is high, but the adaptability decreases for applications requiring reflectance information
Solution Approach 1:
The ranging system is designed with multi-functionality by simultaneously providing distance measurement and reflectance determination capabilities. The same hardware components (light source, detector, timing circuitry) are used to gather data for both functions, allowing the system to adapt to various applications such as autofocus, material identification, and surface characterization without requiring separate dedicated systems
Solution Approach 2:
The system performs self-characterization by automatically measuring and calculating target reflectance properties during the normal ranging operation. The reflectance information is derived from the same reflected light intensity measurements used for distance calculation, allowing the system to provide enhanced functionality without requiring additional calibration procedures or external reference measurements
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
The solution effectively calculates target reflectance, enhancing the accuracy of distance measurements and enabling applications like autofocus and ink level detection, improving the functionality of ranging systems.
Implementation Method 1
A distance to the target is determined based upon time elapsed between activating the ranging light source and detecting the reflected ranging light
Implementation Method 2
Reflected light from the target is detected using the reflected light detector, with the reflected light being a portion of the ranging light that reflects from the target back toward the reflected light detector
Data Source
AI summary
An electronic device includes a ranging light source and a reflected light detector. A logic circuit causes the ranging light source to emit ranging light at a target. Reflected light from the target is detected using the reflected light detector, with the reflected light being a portion of the ranging light that reflects from the target back toward the reflected light detector. An intensity of the reflected light is determined using the reflected light detector. A distance to the target is determined based upon time elapsed between activating the ranging light source and detecting the reflected ranging light. Reflectance of the target is calculated, based upon the intensity of the reflected light and the distance to the target.