Range Finding Apparatus Using Dual-Wavelength Time-of-Flight Detection
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Solution Overview
Problem
Existing range finding technologies face challenges in suppressing the influence of ambient light, particularly in outdoor environments, due to the complexity and cost of configurations that require multiple light-emitting units and filters, and are not suitable for small-sized electronic devices.
Innovation Solution
A range finding apparatus that concurrently emits light of two different wavelengths, using a light source device with a two-dimensionally arranged pixel array to detect time periods for distance calculation, where pixels with varying sensitivities and optical bandpass filters are used to effectively mitigate ambient light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple light-emitting units and filters are used to suppress ambient light influence, then the ability to suppress ambient light interference is improved, but the device complexity and size increase
Solution Approach 1:
The patent uses a single light-emitting unit that changes its emission wavelength over time, alternating between a first wavelength and a second wavelength. By changing the wavelength parameter dynamically, the system achieves the ambient light suppression capability of multiple wavelengths without requiring multiple physical light-emitting units, thus reducing device complexity while maintaining the ability to suppress ambient light interference
Solution Approach 2:
A single light-emitting unit performs multiple functions by emitting different wavelengths at different time periods. The same unit that emits at the first wavelength during a first time period emits at the second wavelength during a second time period, making the single unit universal for both wavelength emissions and eliminating the need for separate dedicated units for each wavelength
2Object-affected harmful factors
If multiple light-emitting units and filters are used to suppress ambient light influence, then the ability to suppress ambient light interference is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs a single light-emitting unit capable of dynamically changing its emission wavelength between a first wavelength and a second wavelength. This parameter change approach eliminates the need to manufacture and assemble multiple separate light-emitting units and corresponding filters, significantly reducing manufacturing complexity and cost while maintaining effective ambient light suppression capability
3Device complexity
If a light-emission diode whose light-emitting wavelength changes with temperature is used, then the configuration is simplified, but the measurement precision decreases due to inability to suppress ambient light at specific wavelengths
Solution Approach 1:
The patent implements periodic switching between emitting at the first wavelength and emitting at the second wavelength through controlled time periods. This periodic action allows the system to systematically alternate wavelengths, enabling the processor to distinguish between reflected signal light and ambient light by analyzing temporal patterns, thereby maintaining measurement precision while using a simplified single-unit configuration
Solution Approach 2:
The system uses the temporal information of when light is emitted versus when reflected light is detected to distinguish signals. By comparing the timing of emitted light at different wavelengths with the timing of detected reflected light, the processor can identify and filter out ambient light interference, maintaining measurement precision through timing-based feedback rather than relying on temperature-dependent wavelength drift
4Device complexity
If a single wavelength is used for range finding, then the device complexity is reduced, but the ability to suppress ambient light influence is insufficient
Solution Approach 1:
The patent employs periodic switching between two wavelengths through controlled time periods. The light-emitting unit emits at the first wavelength during a first time period and at the second wavelength during a second time period. This periodic multi-wavelength approach enables the processor to distinguish reflected signals from ambient light by analyzing temporal patterns, achieving effective ambient light suppression while maintaining a simple single-unit configuration
Solution Approach 2:
The system dynamically changes the emission wavelength parameter over time, alternating between a first wavelength and a second wavelength. This parameter change enables the same light-emitting unit to effectively combat ambient light at different wavelengths sequentially, achieving the ambient light suppression benefit of multi-wavelength systems while maintaining the simplicity of a single physical unit
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 enables efficient range finding with reduced noise interference and cost, suitable for integration in small electronic devices, by using a compact design that effectively suppresses ambient light influence using pixels with different sensitivities and wavelengths.
Implementation Method 1
a light source device capable of concurrently emitting light of a first wavelength and light of a second wavelength
Implementation Method 2
measuring a time difference between a time when light was emitted and a time when reflected light was detected
Implementation Method 3
pixels with varying sensitivities and optical bandpass filters are used to effectively mitigate ambient light interference
Implementation Method 4
a light-receiving part that includes a pixel array in which pixels are two-dimensionally arranged, and that detects incident of light on the pixels
Data Source
AI summary
Disclosed in a range finding apparatus that can efficiently perform range finding that uses light of different wavelengths. The range finding apparatus comprises a light source device capable of concurrently emitting light of a first wavelength and light of a second wavelength that is longer than the first wavelength and computes distance information based on a time period from when range finding is started until when incident of light on a pixel of a light receiving part is detected. In a pixel array of the light receiving part, a first pixel configured to receive light of the first wavelength and a second pixel configured to receive light of the second wavelength are two-dimensionally arranged.