Traffic Light LED Signal Measurement Using Optical Waveguide
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Solution Overview
Problem
Existing traffic signal systems with light-emitting diodes (LEDs) face challenges in accurately measuring the emitted light due to external extraneous light interference, making it difficult to determine if the light output meets minimum standards.
Innovation Solution
Incorporating a light guide to direct a portion of the emitted signal light to a photodetector, allowing for flexible placement to minimize extraneous light influence, and using multiple light guides and photodetectors to differentiate and calculate out extraneous light components, with optical elements like lenses for efficient imaging and coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photodetector is placed near the LED to measure emitted light, then measurement accessibility is improved, but extraneous light interference increases
Solution Approach 1:
The patent segments the light measurement function by using a light guide to separate the measurement path from the signal emission path. The light guide captures a portion of the LED emission and directs it to the photodetector, allowing the photodetector to be positioned away from the LED while still measuring the emitted light accurately.
Solution Approach 2:
The light guide acts as an intermediary between the LED and the photodetector. It transfers a controlled portion of the emitted light to the photodetector, enabling precise measurement while isolating the photodetector from extraneous light sources that would otherwise interfere with the measurement.
2Reliability
If the photodetector is positioned to avoid extraneous light, then measurement reliability is improved, but installation flexibility is reduced
Solution Approach 1:
The light guide serves as a flexible intermediary that can be routed to accommodate various installation positions. It maintains the connection between the LED and photodetector while allowing the photodetector to be positioned in locations that minimize extraneous light interference, thus preserving both reliability and installation flexibility.
Solution Approach 2:
The light guide extends the measurement capability into a different spatial dimension, allowing the photodetector to be positioned away from the LED in three-dimensional space. This enables installation in positions that are optically isolated from extraneous light while still capturing the emitted signal light through the light guide.
3Measurement precision
If multiple light guides and photodetectors are used to differentiate extraneous light, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses multiple light guides and photodetectors to segment the measurement of different light components. One photodetector measures the total light (signal plus extraneous), while another measures only extraneous light, allowing the signal light to be calculated by subtraction. This segmentation enables accurate differentiation of light sources.
Solution Approach 2:
The system uses feedback from multiple photodetectors to calculate and compensate for extraneous light interference. By continuously measuring both the total light and the extraneous light separately, the system can dynamically determine the actual signal light intensity, improving measurement accuracy through this feedback mechanism.
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
Enables precise measurement of the light emitted by LEDs, reducing the impact of external light and ensuring compliance with standards by isolating signal light from extraneous light, thereby improving measurement accuracy and reliability.
Implementation Method 1
a light guide (118) for guiding part of the emitted signal light (110) from the diode to the photodetector
Implementation Method 2
a photodetector (113), and a light guide (118) for guiding part of the emitted signal light (110) from the diode to the photodetector so that the photodetector can measure the part of the emitted signal light guided away
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a signal generator for a traffic light, comprising: - a light emitting diode (109) for emitting a signal light; - a photodetector (113); and - an optical waveguide (118) for guiding a portion of the emitted signal light from the diode to the photodetector so that - the photodetector can measure the portion of the emitted signal light that is guided thereto.