Phosphor-Based Optical Noise Reduction in Sensing Systems

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Solution Overview

Problem

Conventional optical sensing systems face challenges with optical noise reduction, leading to false detections and reduced reliability, especially in environments with lambertian surfaces and cross-talk between sensors, which limits their effectiveness in manufacturing and other applications.

Innovation Solution

Incorporating a phosphor-based layer in the transmitter or receiver of optical sensors, utilizing nano-phosphors and quantum dot phosphors to shift stray reflected light wavelengths outside the detection range, thereby reducing false signals and improving signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sensors are detuned or modified to limit capabilities, then false detections are reduced, but sensing range and reliability are compromised

Engineering Contradiction:
Improvedetection accuracyVSAvoidsensing range
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by modifying the optical characteristics of the sensor system through phosphor-based wavelength shifting. By changing the wavelength parameter of the detected light, the system can maintain full sensing range while achieving selective detection that prevents false positives from lambertian surfaces and other noise sources.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces phosphor material as an intermediary between the optical sensor and the target. This phosphor layer absorbs light at one wavelength and re-emits at a different wavelength, acting as a mediator that enables the sensor to distinguish between valid targets and noise sources without limiting the sensing range.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Area of stationary object

If sensors are placed adjacent to each other, then space is efficiently used, but cross-talk between sensors increases

Engineering Contradiction:
Improvesensor placement densityVSAvoidcross-talk
Core Design Contradiction:
Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent changes the wavelength parameter of light detection for each sensor by using different phosphor materials with distinct emission characteristics. This allows multiple sensors to be placed adjacent to each other without cross-talk, as each sensor detects a unique wavelength signature.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by assigning different phosphor-based wavelength shifting characteristics to different sensors or sensor regions. Each sensor has a localized wavelength detection profile, enabling dense sensor placement while maintaining individual sensor independence and eliminating cross-talk interference.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If conventional filtering methods are used, then some noise is reduced, but signal quality and detection accuracy deteriorate

Engineering Contradiction:
Improveoptical noiseVSAvoidsignal quality
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

Instead of filtering based on intensity or temporal characteristics, the patent changes the wavelength parameter of the detected light through phosphor conversion. This enables selective noise reduction while preserving signal quality, as the wavelength shifting selectively targets noise sources like lambertian reflections while maintaining detection of valid targets.

Inventive Principle:
Principle #35Parameter changes

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 phosphor-based layer effectively filters out stray light and reduces cross-talk between sensors, enhancing the accuracy and reliability of optical sensing systems by preventing false detections and improving signal quality.

Implementation Method 1

Incorporating a phosphor-based layer in the transmitter or receiver of optical sensors, utilizing nano-phosphors and quantum dot phosphors to shift stray reflected light wavelengths outside the detection range

Methodology Applied
Scientific EffectWavelength shifting: Photoluminescence

Data Source

PatentEP2535741B1System and method for reduction of optical noise
Publication Date: 2019.12.18 ROCKWELL AUTOMATION TECH INC
  • EP2535741B1 patent drawingFigure 1~2
  • EP2535741B1 patent drawingFigure 3~5
  • EP2535741B1 patent drawingFigure 6~8

AI summary

A system for reducing optical noise is described comprising a first transmitter having a first transmitter lens and a first optical housing with a first transmitter aperture, a first light source for emitting a first light; and a first phosphor-based layer positioned proximate to the first transmitter aperture and between the first light source and the first lens. A method for reducing optical noise between devices is described comprising generating a first light from a first light source of a first transmitter, passing the first light through a first phosphor based layer, shifting the wavelength of the first light to a first selected wavelength, emitting the shifted first light from the first transmitter, generating a second light from a second light source of a second transmitter, passing the second light through a second phosphor based layer, shifting the wavelength of the second light to a second selected wavelength, different than the first wavelength, emitting the shifted second light from the second transmitter, receiving the shifted second light at the first receiver;passing the second light through a third phosphor-based layer, shifting the wavelength of the second light to a wavelength that exceeds or substantially exceeds the detection range of first receiver, and passing the second light through the first receiver without detection.