Light Sensor With Partially Opaque Optic For Vehicle Rearview

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Solution Overview

Problem

Existing light sensors for vehicle rearview assemblies face challenges with noise reduction, electromagnetic interference immunity, dual voltage operating capability, static protection, and stability under power fluctuations, which affect their accuracy and reliability in measuring light intensity.

Innovation Solution

The design incorporates a light-to-pulse circuit with a shielded light transducer to reduce noise, a low pass filter for EMI immunity, a one shot logic circuit for consistent output, a bandgap voltage reference circuit for stable voltage generation, and a capacitor for static protection, allowing operation at dual voltage levels and improved stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a light sensor is used in vehicle rearview assemblies, then light intensity measurement is achieved, but noise and electromagnetic interference reduce measurement precision

Engineering Contradiction:

Improvelight intensity measurement accuracyVSAvoidnoise and electromagnetic interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A secondary optical element is introduced as an intermediary between the light source and the light sensor. This element includes a tint material that is substantially color neutral for attenuating light, which also serves to reduce noise and electromagnetic interference reaching the sensor, thereby improving measurement precision without significantly blocking the target light

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful factors (noise and electromagnetic interference) are separated from the useful light signal by using the secondary optical element with tint material. The tint material selectively attenuates certain wavelengths and interference while allowing the primary light signal to pass through, effectively extracting the useful signal from the harmful environment

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If the light sensor operates in varying voltage conditions, then adaptability is improved, but stability under power fluctuations deteriorates

Engineering Contradiction:

Improvedual voltage operating capabilityVSAvoidstability under power fluctuations

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The light sensor is designed to operate across varying voltage conditions by incorporating circuitry that can adapt to different power levels. The secondary optical element and associated components are configured to maintain stable optical performance despite voltage fluctuations, allowing the sensor to function reliably in dual voltage environments while preserving measurement stability

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the light sensor is exposed to direct light, then measurement capability is improved, but susceptibility to glare and overexposure increases

Engineering Contradiction:

Improvelight intensity detection capabilityVSAvoidglare and overexposure susceptibility

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The secondary optical element is designed with spatially varying optical properties. The tint material is positioned and configured to provide different levels of attenuation in different regions, allowing the sensor to maintain sensitivity to legitimate light sources while blocking direct glare and overexposure from specific directions. This local differentiation of optical quality enables selective light management

Inventive Principle:

Principle #3Local quality

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 solution enhances noise performance, reduces electromagnetic interference, ensures consistent output, and provides greater stability and reliability in light intensity measurement across varying voltage conditions, improving the overall performance of light sensors in vehicle rearview assemblies.

Implementation Method 1

the secondary optical element including a tint material that is substantially color neutral for attenuating light passing therethrough

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

a light sensor for outputting an electrical signal representing intensity of light impinging upon a light-receiving surface of the light sensor

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11017741B2Light sensor having partially opaque optic

Publication Date: 2021.05.25 GENTEX CORP

AI summary

A rearview assembly for a vehicle is provided that includes: a housing configured for mounting to the vehicle; a rearview element disposed in the housing that displays images of a scene exterior of the vehicle; a light sensor assembly disposed in the housing; and a controller for receiving the electrical signal of the light sensor and for adjusting a brightness of the images displayed by the rearview element. The light sensor includes a light sensor for outputting an electrical signal representing intensity of light impinging upon a light-receiving surface of the light sensor, and a secondary optical element configured to receive light, wherein the light passes through the secondary optical element to the light sensor, the secondary optical element including a tint material that is substantially color neutral for attenuating light passing therethrough.