Head Posture Detection Using Lens Reflections

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Solution Overview

Problem

Current methods for determining the posture characteristics of a spectacle wearer are cumbersome, require specialized equipment, and are sensitive to temperature variations, leading to unreliable measurements and high manufacturing and maintenance costs.

Innovation Solution

A method using a light source and a simple image sensor to determine posture characteristics by analyzing reflections on the optical faces of the lenses, eliminating the need for tracking systems and reducing sensitivity to temperature changes, allowing for easy implementation and high reliability in measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a tracking system is equipp ed on the eyeglass frame to determine yaw angle, then the posture characteristic can be determined, but the device complexity increases and requires careful fixation and specialized expertise

Engineering Contradiction:
Improveyaw angle measurementVSAvoidtracking system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the measurement target from the eyeglass frame itself and places it on the pupil reflections instead. By using the pupil reflections as the measurement reference point rather than requiring frame-mounted tracking systems, the solution eliminates the complexity of fixing and locating tracking systems on various frame shapes while maintaining measurement precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses optical copying by capturing images of the eyeglass wearer's face with the frame and pupils, then processing these images to locate pupil reflections and calculate yaw angle. This replaces physical tracking systems with image-based optical measurement, eliminating the need for specialized hardware on the frame.

Inventive Principle:
Principle #26Copying

2Measurement precision

If stickers are affixed to the lenses to detect positions, then lens position can be determined, but the device complexity increases and automatic localization becomes difficult

Engineering Contradiction:
Improvelens position detectionVSAvoidtracking system with stickers
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the measurement function from frame-mounted or lens-mounted tracking systems and relocates it to the pupil reflections. By measuring the position of pupil reflections instead of requiring physical markers on the frame or lenses, the solution achieves lens and frame position detection without adding stickers or tracking systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses optical copying through image capture and processing to detect lens positions. Instead of physical stickers, the system captures images and processes them to locate lens edges and determine frame position, converting a physical marking problem into an image processing solution.

Inventive Principle:
Principle #26Copying

3Measurement precision

If two separate cameras are used to detect lens positions, then three-dimensional posture characteristics can be obtained, but the manufacturing precision requirements increase and maintenance becomes more complex

Engineering Contradiction:
Improvethree-dimensional posture characteristicsVSAvoidcamera positioning
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent makes the single image sensor perform multiple functions: capturing facial images for pupil location, detecting lens positions through edge detection, and determining three-dimensional posture characteristics through image processing. This replaces the need for multiple specialized cameras while achieving the same measurement capabilities.

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

Solution Approach 2:

The patent uses digital image processing to create three-dimensional information from two-dimensional images. By processing the captured images to locate pupil reflections and lens edges, and calculating spatial relationships, the system achieves 3D posture measurement without requiring physically separated 3D cameras.

Inventive Principle:
Principle #26Copying

4Measurement precision

If neon tubes and flash lamps are used for illumination, then the device can determine posture characteristics, but the device complexity increases and temperature sensitivity affects measurement accuracy

Engineering Contradiction:
Improveposture characteristic determinationVSAvoidmultiple light sources
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the single light source perform multiple illumination functions: illuminating the facial features for pupil detection, providing sufficient light for image capture, and enabling temperature-stable operation. This replaces multiple specialized light sources with a single multi-functional illumination system.

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

5Measurement precision

If manual location of tracking system is performed, then measurement can be completed, but the loss of time increases and productivity decreases

Engineering Contradiction:
Improvetracking system locationVSAvoidmeasurement speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent implements automatic image processing that self-locates the pupil reflections and lens edges without human intervention. The processing unit automatically captures images, processes them to identify key features, and calculates posture characteristics, eliminating the need for opticians to manually locate tracking systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent uses automated optical recognition and image processing to copy and analyze the visual information from the captured images. The system automatically detects pupil reflections and lens positions through algorithmic image processing, replacing manual visual inspection and measurement.

Inventive Principle:
Principle #26Copying

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 method provides reliable and efficient determination of posture characteristics with reduced manufacturing and maintenance costs, enabling accurate personalized optical design for corrective lenses without the need for specialized expertise.

Implementation Method 1

analyzing reflections on the optical faces of the lenses

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2822451B1Method for determining at least one head posture characteristic of a person wearing spectacles
Publication Date: 2021.06.02 ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
  • EP2822451B1 patent drawingFigure 1~3
  • EP2822451B1 patent drawingFigure 4
  • EP2822451B1 patent drawingFigure 5~7

AI summary

The invention relates to a method for determining at least one characteristic relating to the posture of the head (10) of a person (1) wearing spectacles (100) comprising a frame (110) and two lenses (150G, 150D), using a determining device comprising an image sensor, at least one light source and a computation unit. According to the invention, the method comprises steps of: a) acquiring an image (301) of at least part of the wearer's head, in which the spectacles are illuminated by the light source; b) in the image, locating reflections (160D, 160G, 161D, 161G) from the light source, reflected by the two lenses of the spectacles; and c) deducing the wearer's head posture characteristic in relation to the image sensor, as a function of the position of the reflections in the image.