Shared-Window Optical Layers Using Acceptance Angles to Reduce Crosstalk

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Solution Overview

Problem

Existing pulse oximetry systems suffer from optical crosstalk and low signal-to-noise ratio due to unwanted light signals reflecting off device interfaces and superficial layers, leading to erroneous measurements.

Innovation Solution

Implementing light restriction designs with optical layers, films, and lenses that include accepting and blocking sections to selectively allow light within specific acceptance angles and block light outside these angles, utilizing variations in optical and structural properties to reduce or eliminate crosstalk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If light restriction designs with optical layers and films are implemented, then measurement precision and signal-to-noise ratio are improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The optical layer is divided into multiple distinct sections: a first section with a first acceptance angle and a second section with a second acceptance angle. This segmentation allows each section to independently control light from different directions, improving measurement precision by selectively accepting relevant light while blocking crosstalk, without requiring a complete redesign of the entire optical system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the optical layer are assigned different optical properties, specifically different acceptance angles. The first section has a first acceptance angle optimized for one measurement direction, while the second section has a second acceptance angle optimized for another direction. This local differentiation improves measurement accuracy for multiple parameters simultaneously while maintaining a relatively simple overall device structure.

Inventive Principle:
Principle #3Local quality

2Object-generated harmful factors

If optical films with spatially varying acceptance angles are used, then crosstalk between optical components is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
ImprovecrosstalkVSAvoidmanufacturing precision
Core Design Contradiction:
Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The optical layer is segmented into discrete first and second sections, each with defined acceptance angles. This segmentation simplifies the manufacturing process compared to creating a continuously varying gradient, as each section can be manufactured with standard precision tolerances. The clear boundaries between sections make quality control and inspection more straightforward while still effectively blocking crosstalk between different optical measurement paths.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If multiple acceptance angles are implemented in different regions, then signal-to-noise ratio is enhanced, but ease of manufacture decreases

Engineering Contradiction:
Improvesignal-to-noise ratioVSAvoidease of manufacture
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent combines multiple functional sections into a single integrated optical layer rather than using separate optical components for each acceptance angle. The first and second sections are merged into one continuous layer with different regional properties, which simplifies assembly and manufacturing compared to integrating multiple discrete optical elements. This merging maintains the signal-to-noise ratio enhancement while improving ease of manufacture.

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

Enhances measurement accuracy and signal-to-noise ratio by minimizing unwanted light interference, thereby improving the reliability of physiological signal detection.

Implementation Method 1

an optical layer including a first section configured to allow light within a first acceptance angle to pass through the optical layer and a second section configured to allow light within a second acceptance angle to pass through the optical layer

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

each region configured to prevent light having an angle of incidence outside of the plurality of viewing angles from passing through

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP4170393B1Light restriction designs in optical sensing applications having shared windows
Publication Date: 2025.08.13 APPLE INC
  • EP4170393B1 patent drawingFigure 1A~1C
  • EP4170393B1 patent drawingFigure 2A~2B
  • EP4170393B1 patent drawingFigure 2C~2D

AI summary

This relates to an electronic device configured for optical sensing having shared windows and including light restriction designs. The light restriction designs can include one or more of optical layers, optical films, lenses, and window systems configured to reduce or eliminate crosstalk between optical components. A plurality of accepting sections and a plurality of blocking sections can be employed to selectively allow light having an angle of incidence within one or more acceptance viewing angles and block light with angles of incidence outside of the acceptance viewing angles. In some examples, the light restriction designs can include variations in optical and structural properties can allow the light restriction designs to have spatially varying acceptance angles. Variations in structural properties can include, but are not limited to, differences in widths, heights, and/or tilts of the accepting sections and/or blocking sections.