Optical Mirror Detection Using Brewster-Angle Polarisation

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Solution Overview

Problem

In smart home environments, mirrors are often used during personal care routines but are difficult to detect efficiently, hindering optimal interaction and coordination with other smart devices.

Innovation Solution

A system utilizing an optical sensor arrangement to measure polarized light and generate data for analysis by a processor to detect the presence of a mirror, leveraging the polarizing properties of mirrors at Brewster's angle to accurately identify their presence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional sensors are used to detect mirrors, then the detection capability is insufficient, but using polarisation-based optical sensors improves detection reliability

Engineering Contradiction:
Improvemirror detection reliabilityVSAvoidsensor arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical or simple optical sensors with a polarisation-based optical sensor system. The sensor arrangement measures polarisation states of light reflected from surfaces to distinguish mirrors from other reflective surfaces. This substitution enables reliable mirror detection by exploiting the unique polarisation characteristics of mirror reflections, particularly at Brewster's angle, while maintaining a relatively simple device structure through the use of standard polarisation measurement techniques.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If multiple sensors are used to improve detection accuracy, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improvemirror detection precisionVSAvoidsensor arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent measures light polarisation in multiple dimensions by detecting different polarisation states (s-polarised and p-polarised light components). Instead of using multiple physical sensors at different locations, the system uses a single optical sensor arrangement that measures the polarisation state of reflected light, which contains dimensional information about the reflecting surface. This approach achieves high measurement precision for mirror detection while avoiding the complexity of multiple separate sensors.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 reliable detection of mirrors, allowing for optimized settings and interactions with personal care devices, enhancing user experience and device coordination.

Implementation Method 1

an optical sensor arrangement configured to measure incoming light of at least one polarity and to generate polarisation data describing an intensity of the light of the at least one polarity

Methodology Applied
Scientific EffectPolarisation: Polarisation

Implementation Method 2

shiny surfaces, e.g., mirrors, will polarise unpolarised light if they hit the mirror at or close to Brewster's angle

Methodology Applied
Scientific EffectBrewster's angle: Brewster's Angle

Implementation Method 3

mirrors are capable of polarising unpolarised light from natural light or room lights

Methodology Applied
Scientific EffectPolarisation by reflection: Polarisation

Data Source

PatentEP4621448A1Detecting mirror with polarisation
Publication Date: 2025.09.24 KONINKLIJKE PHILIPS NV
  • EP4621448A1 patent drawingFigure 1A~2
  • EP4621448A1 patent drawingFigure 3~4
  • EP4621448A1 patent drawingFigure 5~6

AI summary

Proposed concepts thus aim to provide schemes, solutions, concepts, designs, methods and systems pertaining to detecting the presence of a mirror. In particular, embodiments aim to provide a system for detecting the presence of a mirror by analysing measured polarised light. This is because shiny surfaces, e.g., mirrors, will polarise unpolarised light if they hit the mirror at or close to Brewster's angle. The presence of polarised light can thus be used to infer the presence of a mirror. In other words, it is proposed that by measuring incoming light of at least one polarity (i.e., at least light polarised in a certain direction), the presence of a mirror can be detected. This is because mirrors are capable of polarising unpolarised light from natural light or room lights, and thus the presence of polarised light can be used to detect the presence of a mirror.