Polarization-Sensitive Light Sensor for Phosphor Damage Detection

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Solution Overview

Problem

Existing lighting devices, particularly vehicle lighting systems, are unable to detect slight damage to the luminophore volume efficiently, making early detection of damage or detachment impractical.

Innovation Solution

A lighting device with a polarized primary light beam, a phosphor volume for wavelength conversion, and a polarization-sensitive light sensor with a photodiode and filters, allowing for early detection of phosphor volume damage or detachment by measuring changes in polarization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional light sensors are used in lighting devices, then the device can detect light intensity, but it cannot detect slight damage to the phosphor volume or polarization changes

Engineering Contradiction:
Improvedetection capabilityVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The light sensor is segmented into multiple functional components: a photodiode for light detection, a primary light filter for wavelength selection, and a polarization filter for polarization state detection. This segmentation allows each component to perform a specific function, enabling precise detection of polarization changes while keeping the overall device structure manageable and modular.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If advanced detection methods are implemented to detect phosphor volume damage, then measurement precision improves, but device complexity and cost increase

Engineering Contradiction:
Improvedamage detection accuracyVSAvoidsystem structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The lighting device performs self-diagnostics by using its own emitted polarized light as the detection source. The light sensor detects polarization changes in the light that has interacted with the phosphor volume, allowing the system to monitor its own operational status and detect phosphor damage without requiring external detection equipment.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The polarization filter acts as an intermediary element that translates the physical state of the phosphor volume into a detectable polarization signal. By placing the polarization filter in the light path between the phosphor volume and the photodiode, it mediates the interaction between the light and the detector, enabling indirect detection of phosphor damage through polarization state changes.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a polarization-sensitive light sensor with filters is used, then early detection of phosphor volume damage is enabled, but manufacturing complexity increases

Engineering Contradiction:
Improveearly damage detectionVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the light detection function and polarization detection function into a single integrated light sensor assembly. The photodiode, primary light filter, and polarization filter are combined in one compact unit that can be manufactured and assembled as a single module, reducing the number of separate components and simplifying the manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

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 early and inexpensive detection of phosphor volume destruction or detachment, ensuring safety and reliability in vehicle lighting systems by using simple and cost-effective components.

Implementation Method 1

at least one light source for emitting a polarized primary light beam

Methodology Applied
Scientific EffectPolarization: Polarisation

Implementation Method 2

the light sensor has a photodiode

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 3

which has a primary light filter

Methodology Applied
Scientific EffectOptical Filtering: Filter (optical)

Data Source

PatentEP3172485B1Lighting device having at least one light sensor
Publication Date: 2019.10.09 OSRAM GMBH
  • EP3172485B1 patent drawingFigure 1
  • EP3172485B1 patent drawingFigure 2
  • EP3172485B1 patent drawingFigure 3

AI summary

The invention relates to a lighting device (1) comprising at least one light source (2) for emitting a polarized primary light beam (P), at least one luminescent material volume (6) for at least partially converting primary light of the primary light beam (P) into secondary light (S) having a different wavelength, which luminescent material volume is arranged in a path of at least a primary light beam (P), and at least one light sensor (7-9), which is arranged at least in a part of an original path of the primary light beam (P) after the location of the luminescent material volume, wherein the light sensor (7-9) is sensitive at least to the primary light and is polarization-sensitive. The invention can, in particular, be applied to vehicle lighting devices, in particular vehicle lamps, e.g., headlamps, or modules thereof.