Nanostructured Image Sensor Autofocus With Wavelength Color Separation
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Solution Overview
Problem
Conventional color image sensors face inefficiencies in light utilization and focusing due to the absorption of non-corresponding colors by color filters, and auto focusing methods like PDAF are less accurate but faster, while contrast detection AF is more accurate but slower.
Innovation Solution
An image sensor with a light sensor array, a transparent layer, a color separation element, and a focusing element featuring a nanostructure that performs auto focusing, where the focusing element is integrated on the same layer as the color separation element and includes a binary lens structure with nanostructures in concentric circles, allowing for precise focusing and improved light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are used to detect colors in image sensors, then color detection capability is improved, but light utilization efficiency decreases due to absorption of non-corresponding colors
Solution Approach 1:
The patent changes the physical state and optical properties of the light sensor by introducing a nanostructure with specific refractive index differences between core and cladding layers. This enables wavelength-dependent mode confinement that achieves color separation without absorbing light, thereby maintaining high light utilization efficiency while improving color detection capability.
Solution Approach 2:
The patent employs a composite nanostructure consisting of a core layer and a cladding layer with different refractive indices. This composite structure creates distinct propagation modes for different wavelengths, enabling efficient color separation while preserving light energy that would otherwise be absorbed by conventional color filters.
2Speed
If phase detection auto-focusing is used to focus images, then focusing speed is improved, but focusing accuracy decreases compared to contrast detection
Solution Approach 1:
The patent segments the light from different object distances into different propagation modes within the nanostructure. By detecting the spatial distribution of these modes, the system achieves both rapid focusing (like PDAF) and high accuracy (like CDAF), resolving the contradiction between speed and precision.
Solution Approach 2:
The patent introduces a nanostructure as an intermediary element that mediates between the incoming light and the sensor. This nanostructure encodes depth information through mode differentiation, enabling the system to achieve accurate focusing without the speed penalty of traditional contrast detection methods.
3Device complexity
If conventional light sensors are used without nanostructures, then device simplicity is maintained, but light distribution and focusing accuracy are insufficient
Solution Approach 1:
The patent transitions from conventional two-dimensional pixel arrays to a three-dimensional nanostructure with core-cladding configuration. This dimensional enhancement enables mode-based light separation and depth encoding, significantly improving focusing accuracy while adding only a single nanostructure layer to the existing sensor architecture.
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 light distribution efficiency and auto focusing accuracy by separating incident light into colors based on wavelength, enabling faster and more precise focusing, particularly in regions with different incidence angles.
Implementation Method 1
a color separation element provided on the transparent layer and configured to separate the incident light into light of a plurality of colors based on a wavelength band
Implementation Method 2
a light sensor array including a plurality of light sensors configured to detect an incident light and convert the incident light into an electrical signal
Implementation Method 3
a focusing element including a nanostructure in a region corresponding to at least one pixel among the plurality of pixels and configured to perform auto focusing
Data Source
AI summary
Provided is an image sensor including a light sensor array including a plurality of light sensors configured to detect an incident light and convert the incident light into an electrical signal, the plurality of light sensors being are provided in a plurality of pixels, a transparent layer provided on the light sensor array, a color separation element provided on the transparent layer and configured to separate the incident light into light of a plurality of colors based on a wavelength band, and a focusing element including a nanostructure in a region corresponding to at least one pixel among the plurality of pixels and configured to perform auto focusing.