Four-Lens Assembly With Infrared Band-Pass Stray Light Filtering

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Solution Overview

Problem

Optical devices face challenges in controlling reflection, refraction, and scattering in lens assemblies, leading to reduced accuracy in distance measurement and image quality, particularly in electronic devices with multiple cameras.

Innovation Solution

A lens assembly with at least four lenses and a band pass filter is designed to suppress stray light by blocking light outside the measurement wavelength range, ensuring a specific conditional equation is met for lens positioning and filter transmittance, enhancing distance measurement accuracy and image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a TOF optical system is added for distance measurement, then object recognition and 3D scanning functions are enhanced, but stray light from irregular reflection, refraction, and scattering in the lens assembly deteriorates measurement accuracy

Engineering Contradiction:

Improvedistance measurement accuracyVSAvoidstray light

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes stray light from the optical path by introducing a band pass filter that selectively transmits only the measurement wavelength range (800nm-1000nm) while blocking other wavelengths. This extraction principle directly addresses the harmful stray light generated by irregular reflection, refraction, and scattering in the lens assembly, thereby improving distance measurement accuracy without compromising the TOF function

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The band pass filter acts as an intermediary component between the lens assembly and the image sensor. It mediates the optical path by allowing only the desired measurement wavelength to pass through while blocking stray light of other wavelengths. This intermediary approach resolves the contradiction by filtering harmful elements without affecting the core measurement function

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple lenses are arranged in the lens assembly, then image quality and optical performance are improved, but control of reflection, refraction, and scattering becomes more difficult

Engineering Contradiction:

Improveimage qualityVSAvoidlens assembly control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by specifying precise transmittance requirements for each lens in the assembly. At least one lens is designed with 0%-10% transmittance for visible light (400nm-700nm) and specific transmittance for infrared light (800nm-1000nm). This parameter control allows multiple lenses to be arranged while maintaining manageable complexity through standardized optical properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite optical design by combining lenses with different transmittance characteristics. At least one lens is designed with selective transmittance properties that allow it to function both as an imaging element and as a stray light suppressor. This composite approach integrates multiple functions into the lens assembly, improving image quality while maintaining control over reflection, refraction, and scattering

Inventive Principle:

Principle #40Composite materials

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 effectively suppresses stray light, improving distance measurement accuracy and image quality, thereby enhancing functions like object recognition and 3D scanning in electronic devices.

Implementation Method 1

at least one band pass filter having a transmittance of 90% to 98% for at least a portion of light in a wavelength range of 800 nanometer (nm) to 1000 nm

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

For light in a wavelength range of 400 nm to 700 nm, at least one of the lenses may have a transmittance of 0% to 10%

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 3

controlling reflection, refraction, and/or scattering in the lens assembly may be limited, and light (hereinafter, 'stray light') caused by irregular reflection, refraction, and/or scattering in the lens assembly may deteriorate the accuracy

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 4

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 5

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS12418709B2Lens assembly and electronic device comprising same

Publication Date: 2025.09.16 SAMSUNG ELECTRONICS CO LTD

AI summary

A lens assembly is provided. The lens assembly includes an image sensor, at least four lenses successively arranged along an optical axis from an object side toward the image sensor side, and at least one band pass filter having a transmittance of 90% to 90% with regard to at least some of light in the wavelength area of 800˜1000 nm. At least one of the lenses is disposed between the band pass filter and the image sensor. With regard to light in the wavelength area of 400˜700 nm, at least one of the lenses has a transmittance of 0% to 10%, and all of the lenses have an average transmittance of 0% to 5%.