Image Sensor Color Filter Layout for Balanced Autofocus Pixels

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Solution Overview

Problem

Conventional image sensors face challenges in achieving balanced optical properties and effective autofocus functions due to irregularities in color ratio and sensitivity between pixel regions, particularly near the autofocus pixel group, leading to defects in image quality.

Innovation Solution

The design incorporates a unique arrangement of color filters with protrusions on the first and second color filters, where the second color filter has a wider protrusion than the first, and a light-shield pattern to optimize the optical properties and reduce irregularities in color ratio, ensuring balanced sensitivity between pixel regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If color filters are arranged regularly without protrusions, then manufacturing is simple, but optical properties are unbalanced and color ratio irregularities occur between pixel regions

Engineering Contradiction:

Improvecolor ratio uniformityVSAvoidcolor filter structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The color filters are designed with different local structures: first color filters have a first protrusion structure while second color filters have a second protrusion structure. This local differentiation compensates for optical path differences between pixel regions adjacent to autofocus pixels, achieving uniform color ratio and balanced optical properties across the sensor surface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention introduces asymmetric protrusion structures where the first protrusion and second protrusion have different dimensions and configurations. This asymmetry is deliberately designed to counterbalance the asymmetric optical effects caused by proximity to autofocus pixels, thereby achieving symmetric optical performance across different pixel regions.

Inventive Principle:

Principle #4Asymmetry

2Adaptability or versatility

If autofocus pixels are placed between image pixel groups, then autofocus function is enabled, but optical properties and sensitivity become unbalanced in surrounding pixel regions

Engineering Contradiction:

Improveautofocus functionVSAvoidphotosensitivity balance

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

Pixel regions adjacent to autofocus pixels are equipped with specialized protrusion structures on their color filters, while other regions use standard configurations. This local adaptation compensates for the optical interference caused by autofocus pixels, maintaining balanced photosensitivity without sacrificing autofocus capability.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If protrusions are added to color filters to balance optical properties, then photosensitivity is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveoptical property balanceVSAvoidcolor filter fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The color filter array is segmented into different types (first color filters and second color filters) with distinct protrusion structures. Each segment is optimized for its specific location relative to autofocus pixels, allowing systematic manufacturing through specialized patterning processes while achieving overall optical balance.

Inventive Principle:

Principle #1Segmentation

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 enhances the optical properties of the image sensor by reducing light loss and achieving balanced photosensitivity between autofocus and image pixels, resulting in improved autofocus correction and overall image quality.

Implementation Method 1

Each of the unit pixel regions includes a photodiode. The photodiode serves to convert incident light into electrical signals.

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

a microlens section on the first color filter and the second color filter

Methodology Applied

Scientific EffectLens focusing: Lens

Data Source

PatentUS20240021638A1Image sensor

Publication Date: 2024.01.18 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor includes a first pixel group on a substrate and including a plurality of first pixels, a second pixel group on the substrate and including a plurality of second pixels, where at least one of the plurality of first pixels and at least one of the plurality of second pixels are adjacent in a first direction, a first autofocus pixel group between the first pixel group and the second pixel group, the first autofocus pixel group including a first autofocus pixel adjacent to the first pixel group and a second autofocus pixel adjacent to the second pixel group, a first color filter on the first autofocus pixel and the second autofocus pixel, a second color filter on the plurality of second pixels, and a light-shield pattern that separates the first color filter and the second color filter.