Optical Filter Placement for Traffic Light Color Detection

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Solution Overview

Problem

Existing traffic light detection systems in vehicles face challenges in accurately perceiving the color of traffic signals due to issues like color distortion, which can lead to incorrect vehicle responses, potential collisions, and resource consumption by law enforcement.

Innovation Solution

A traffic light detection system configured with a light sensor, a lens, and a filter arranged in a specific configuration, where the filter is positioned between the lens and the light sensor to permit specific wavelengths associated with red, yellow, and green lights, minimizing color distortion and ensuring accurate detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a camera with lens and sensor is used for traffic light detection, then the system can capture images of traffic lights, but color distortion occurs leading to inaccurate detection

Engineering Contradiction:
Improvetraffic light color detection accuracyVSAvoidcolor distortion
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A filter is introduced as an intermediary component between the lens and the sensor. This filter selectively transmits specific wavelengths of light corresponding to traffic light colors (red, yellow, green) while blocking other wavelengths. By placing the filter in this intermediate position, the system eliminates color distortion without requiring changes to the lens or sensor themselves, thereby achieving accurate color detection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the filter is positioned close to the sensor, then color distortion is minimized, but the field of view is restricted

Engineering Contradiction:
Improvecolor detection accuracyVSAvoidfield of view
Core Design Contradiction:
Measurement precisionVSArea of moving object

Solution Approach 1:

The detection system is divided into multiple independent units, each consisting of a lens, filter, and sensor. Each unit can be optimized independently - the filter is positioned close to its corresponding sensor to ensure accurate color detection, while multiple units work together to provide a comprehensive field of view. This segmentation allows the system to achieve both high measurement precision and adequate field of view coverage.

Inventive Principle:
Principle #1Segmentation

3Area of moving object

If multiple lenses and sensors are used to improve field of view, then coverage is enhanced, but system complexity increases

Engineering Contradiction:
Improvefield of view coverageVSAvoidsystem structure
Core Design Contradiction:
Area of moving objectVSDevice complexity

Solution Approach 1:

Multiple identical or similar detection units (lens-filter-sensor assemblies) are used, where each unit performs the same function of detecting traffic light colors. This universal approach allows the system to achieve enhanced field of view coverage through simple replication rather than complex integration, as each module can be manufactured and assembled using the same processes and design templates.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 system effectively detects traffic light colors, enabling vehicles to comply with traffic laws, avoid collisions, and conserve resources by reducing the need for law enforcement intervention and minimizing hardware damage.

Implementation Method 1

The filter may be configured to permit a preconfigured set of wavelengths of light from the environment to be sensed by the light sensor

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

The lens may include a distal end positioned toward an environment and a proximal end that is opposite the distal end and positioned toward the light sensor

Methodology Applied
Scientific EffectLight refraction and focusing: Lens

Data Source

PatentEP3916457B1Sensor and filter configuration to detect specific wavelengths of light
Publication Date: 2025.06.04 ACCENTURE GLOBAL SOLUTIONS LTD
  • EP3916457B1 patent drawingFigure 1
  • EP3916457B1 patent drawingFigure 2A
  • EP3916457B1 patent drawingFigure 2B

AI summary

A sensor arrangement may include a light sensor, a lens, and a filter. The lens may include a distal end positioned toward an environment and a proximal end that is opposite the distal end and positioned toward the light sensor. The filter may be situated between the light sensor and the proximal end of the lens. The filter may be configured to permit a preconfigured set of wavelengths of light from the environment to be sensed by the light sensor.