Three-Element Light Sensor Module for Indoor Light and Sunlight Distinction

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Solution Overview

Problem

Existing light sensors face challenges in accurately distinguishing between indoor light sources and sunlight due to sidewall light leakage caused by unintended secondary and tertiary light rays, which affect performance and lead to misjudgments.

Innovation Solution

A light sensing method using three photodetection elements with different effective photosensitive wavelength ranges, including a full absorption band element, to subtract and calculate ratios of optical signal values, eliminating the need for infrared light band sensing and mitigating sidewall light leakage effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical filters are used to detect light within a specific wavelength range, then measurement precision is improved, but device complexity increases due to unintended secondary and tertiary light rays causing sidewall light leakage

Engineering Contradiction:

Improvelight source identification accuracyVSAvoidoptical filter structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the photodetection function into three separate photodetection elements, each with different effective photosensitive wavelength ranges. This segmentation allows each element to capture specific wavelength components independently, enabling accurate light source identification without requiring complex optical filters to manage sidewall light leakage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by giving each photodetection element distinct photosensitive characteristics tailored to specific wavelength ranges. The first element responds to visible light, the second to infrared, and the third has reduced infrared sensitivity, creating localized spectral sensitivity profiles that eliminate the need for complex filtering structures.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If infrared photodetection is used to distinguish between indoor and sunlight sources, then measurement precision is improved, but reliability deteriorates due to sidewall light leakage affecting detection accuracy

Engineering Contradiction:

Improvelight source type distinction accuracyVSAvoiddetection stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a third photodetection element as an intermediary with reduced infrared sensitivity to mediate the detection process. This element helps differentiate between genuine infrared signals from light sources and spurious signals from sidewall light leakage, thereby improving both measurement precision and detection reliability simultaneously.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite photodetection system combining three elements with different spectral sensitivity profiles. This composite approach allows the system to process multiple wavelength components simultaneously, cross-validate signals, and eliminate false detections from sidewall light leakage, enhancing both accuracy and reliability.

Inventive Principle:

Principle #40Composite materials

3Productivity

If compact design and miniaturization are implemented, then productivity is improved, but object-affected harmful factors increase due to increased sidewall light leakage

Engineering Contradiction:

Improvedevice miniaturization efficiencyVSAvoidsidewall light leakage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical/optical approach of using physical filters and larger sensor structures with a semiconductor-based solution. By utilizing materials with inherently different infrared absorption coefficients and designing at the micro-level, the system achieves compact size while eliminating sidewall light leakage without requiring complex mechanical filter structures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Accurately distinguishes between indoor light sources and sunlight, enhancing accuracy and reducing costs by eliminating the reliance on infrared light band sensing and addressing sidewall light leakage.

Implementation Method 1

a first, second, and third photodetection elements to obtain a first, second, and third optical signal values respectively

Methodology Applied

Scientific EffectPhotodetection: Photoelectric Effect

Implementation Method 2

the third photodetection element is a full absorption band absorbing photodetection element

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20250251276A1Light sensing method and light sensor module thereof

Publication Date: 2025.08.07 SENSORTEK TECH

AI summary

The present application provides a light sensing method and a light sensor module thereof, wherein the light sensing method includes obtaining optical signal values respectively by sensing of a first photodetection element, a second photodetection element, and a third photodetection element, wherein the first photodetection element and the second photodetection element have different effective photosensitive wavelength ranges, and the third photodetection element is a full-absorption band photodetection element. Through this, operation results of the optical signal values may be used to identify types of light sources.