Photonic Crystal Microlens for Image Sensor Light Transmittance

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Solution Overview

Problem

Conventional image sensors with color filters allow only one-third of incident visible light to pass through, reducing the number of photons reaching the photoelectric conversion elements and limiting light transmittance.

Innovation Solution

The image sensor incorporates a photonic crystal structure with protrusions and grooves on the microlenses, allowing specific wavelengths of visible light to be reflected while allowing other wavelengths to pass through to the photoelectric conversion elements, enhancing light transmittance and utilizing the photonic crystal as a reflective color filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a color filter is used per pixel, then color separation is achieved, but light transmittance is reduced to one-third of incident visible light

Engineering Contradiction:

Improvecolor separationVSAvoidlight transmittance

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent replaces the conventional absorptive color filter with a photonic crystal-based microlens that uses optical interference and diffraction effects. The photonic crystal structure creates wavelength-selective reflection through its periodic refractive index modulation, eliminating the need for absorptive dyes and enabling higher light transmittance while maintaining color separation functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The microlens is constructed as a composite structure combining photonic crystal materials with specific refractive indices arranged in periodic patterns. This composite design enables the lens to simultaneously focus light and selectively reflect specific wavelengths, achieving both color separation and high light efficiency in a single integrated component.

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If conventional color filters are used, then wavelength selection is achieved, but the number of photons reaching photoelectric conversion elements is decreased

Engineering Contradiction:

Improvewavelength selectionVSAvoidnumber of photons

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent substitutes absorptive wavelength filtering with photonic crystal-based reflective filtering. The photonic crystal structure uses constructive and destructive interference to reflect specific wavelengths while transmitting others, thereby preserving photon quantity for the desired wavelengths while achieving precise wavelength selection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent converts the typically wasted reflected light into a useful function by designing the photonic crystal microlens to reflect specific wavelengths toward the photoelectric conversion element. This transforms what would be lost reflection into a mechanism for enhancing light capture efficiency and wavelength selectivity simultaneously.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This configuration increases light transmittance to the photoelectric conversion elements, improving the sensitivity and efficiency of the image sensor by allowing more visible light to be utilized, thereby enhancing the image capture capabilities.

Implementation Method 1

A photonic crystal may have a bandgap or a photonic bandgap which blocks light of a specific frequency. For example, when two types of materials with different refractive indexes are periodically arranged at about a half wavelength of a specific light, a photonic bandgap which blocks the specific light is generated.

Methodology Applied

Scientific EffectPhotonic bandgap: Photonic Crystal

Implementation Method 2

the first microlens reflects wavelengths of a first region of visible light and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

the first, second and third microlenses each has a curved surface, protrusions and grooves are arranged in each of the curved surfaces

Methodology Applied

Scientific EffectLight refraction: Refraction

Data Source

PatentUS9455290B2Image sensor including a photonic crystal, an operating method thereof, and a data processing system including the image sensor

Publication Date: 2016.09.27 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor including: a plurality of pixels, wherein a first pixel of the pixels includes: a first photoelectric conversion element; and a first microlens overlapping the first photoelectric conversion element, wherein the first microlens reflects wavelengths of a first region of visible light and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element.