White pcLED Lidar Detection Using Wavelength Segmentation
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Solution Overview
Problem
White phosphor-converted LEDs (pcLEDs) used in lighting systems have a long decay lifetime when driven with short current pulses, affecting the accuracy of lidar distance measurements due to their sensitivity to target color and wavelength, making it difficult to calibrate lidar systems for precise distance correlation with timing signals.
Innovation Solution
A dual-function lighting system using white pcLEDs that performs both lighting and lidar functions by employing a pulse-width modulation scheme with separate wavelength band detection, utilizing blue emission for short-range accuracy and broadband luminescence for long-range detection, and optimizing photodetectors for specific wavelength responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If white pcLEDs are driven with short current pulses for lidar function, then the lighting function is maintained, but the long decay lifetime affects the accuracy of distance measurements
Solution Approach 1:
The patent segments the detection process by separating wavelength band detection - using blue emission detection for short-range measurements and broadband luminescence detection for long-range measurements. This segmentation allows the system to overcome the long decay lifetime limitation by selecting appropriate wavelength bands for different measurement scenarios, thereby maintaining both lighting function stability and distance measurement accuracy.
2Measurement precision
If blue emission is used for short-range detection, then measurement accuracy is improved, but detection capability for long-range targets is reduced
Solution Approach 1:
The patent implements dynamic adaptability by enabling the photodetector system to switch between different wavelength band detection modes based on the measurement requirements. For short-range targets, the system dynamically selects blue emission detection for high precision, while for long-range targets, it dynamically switches to broadband luminescence detection, thereby achieving both high accuracy and wide detection range coverage.
3Adaptability or versatility
If broadband luminescence is used for long-range detection, then detection capability is improved, but measurement precision for short-range targets is reduced
Solution Approach 1:
The patent segments the detection capability by providing separate detection pathways for different wavelength bands. The system can segment the detection process to use broadband luminescence detection specifically for long-range targets while using blue emission detection for short-range targets, thereby achieving both long-range detection capability and short-range measurement precision through appropriate segmentation of the detection function.
4Device complexity
If a single light source is used for both lighting and lidar functions, then device complexity is reduced, but calibration difficulty increases
Solution Approach 1:
The patent addresses calibration difficulty by changing the detection parameter - using wavelength band selection as a controllable parameter. By adjusting which wavelength band is detected (blue emission or broadband luminescence), the system can optimize performance for different ranges without requiring separate light sources. This parameter-based approach simplifies the physical structure while providing systematic methods to manage calibration across different operating conditions.
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
Enhances lidar distance measurement accuracy and sensitivity by using blue emission for close-range and broadband luminescence for long-range detection, maintaining the lighting function without significant impact, and allowing precise temporal profiling of pulsed light signals.
Implementation Method 1
A pcLED typically consists of a LED made from a single chip of a III-V semiconductor material such as indium gallium nitride (InGaN), and emitting light in a narrow wavelength range from about 450 nanometers (nm) to 470 nm
Implementation Method 2
A part of the blue light emitted by the LED is absorbed by a special material such as cerium-doped yttrium-aluminum-garnet ((Y1-aGda)3(Al1-bGab)5012:Ce3+), abbreviated as YAG:Ce. This special material is usually known as a phosphor, and it causes down-conversion of the absorbed blue photons through a photoluminescence process to yield a light emission characterized by a broad spectrum that peaks around the 550-nm wavelength
Implementation Method 3
The portion of the blue light that is not absorbed by the YAG:Ce phosphor escapes to the outside and mixes with the yellow luminescent emission to generate white light
Implementation Method 4
receiving a reflection/backscatter of the emitted light from an object; identifying rapid transients in the reflection/backscatter received; and calculating a distance of the object from the rapid transients received and rapid transients from the pulse-width modulation
Data Source
AI summary
A method for detecting an object using light comprises providing a light source having a function of illuminating an environment. The light source is driven to emit light in a predetermined mode, with light in the predetermined mode being emitted such that the light source maintains said function of illuminating an environment. A reflection/backscatter of the emitted light is received from an object. The reflection/backscatter is filtered over a selected wavelength range as a function of a desired range of detection from the light source to obtain a light input. The presence or position of the object is identified with the desired range of detection as a function of the light input and of the predetermined mode.