Pixel Array Microlens Layout for Four-Direction Autofocus

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Solution Overview

Problem

Existing image sensors face challenges in securing autofocusing in multiple directions while preventing electrical charge saturation and achieving high-quality image generation.

Innovation Solution

The image sensor incorporates a substrate with a pixel array comprising alternating first and second pixel groups, each with unit pixels arranged in a 4×4 array. The first pixel groups have individual microlenses, while the second pixel groups share larger microlenses, enabling autofocusing in four directions and preventing charge saturation through an overflow region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If individual microlenses are provided on each unit pixel, then manufacturing precision is improved, but autofocusing capability in multiple directions deteriorates

Engineering Contradiction:

Improvemicrolens alignment precisionVSAvoidautofocusing capability

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The pixel array is divided into first pixel groups with individual microlenses and second pixel groups with shared microlenses. This segmentation allows different regions to serve different functions: individual microlenses provide precise optical focusing, while shared microlenses enable autofocusing by comparing phase differences across multiple photodiodes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shared microlenses in second pixel groups serve multiple unit pixels simultaneously, enabling the system to perform both image capture and autofocusing operations. By sharing the microlens among multiple photodiodes and comparing their signals, the system achieves autofocusing capability without requiring individual microlenses for each pixel

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If larger microlenses are used for shared pixel groups, then autofocusing capability is improved, but optical loss increases

Engineering Contradiction:

Improveautofocusing capabilityVSAvoidoptical loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Different microlens sizes are applied to different pixel groups based on their functional requirements. First pixel groups use smaller individual microlenses optimized for precise image capture with minimal optical loss, while second pixel groups use larger shared microlenses optimized for autofocusing. This local differentiation allows each region to operate at optimal efficiency for its specific function

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If photodiode size is increased to capture more light, then image quality is improved, but electrical charge saturation occurs

Engineering Contradiction:

Improvelight capture capabilityVSAvoidcharge saturation prevention

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The pixel array is segmented into different pixel groups with different microlens configurations. Second pixel groups with shared microlenses are specifically designed for autofocusing operations where phase difference comparison is performed, allowing these regions to handle higher light intensities without saturation by distributing charges across multiple photodiodes for comparison purposes

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 ensures secure autofocusing in four directions, prevents electrical charge saturation, and generates high-quality images with improved resolution and reduced optical loss.

Implementation Method 1

Each of the plurality of unit pixels may include a photodiode which generates an electrical charge in response to external light that is incident thereon

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS12243883B2Image sensor comprising a pixel array including first pixel groups and second pixel groups with corresponding microlenses of different sizes for autofocusing

Publication Date: 2025.03.04 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor is provided. The image sensor includes: a pixel array including first and second pixel groups, each of which includes unit pixels arranged in 4×4 array, each of the unit pixels including a photodiode provided, and the first and second pixel groups being alternately disposed in multiple directions; a logic circuit configured to acquire pixel signals from the unit pixels; first microlenses provided on corresponding unit pixels in the first pixel groups; and second microlenses provided on four corresponding unit pixels of the unit pixels included in the second pixel groups. Each of the first and second pixel groups includes a device isolation layer provided between the unit pixels, and a color filter provided on the first surface, and each of the second pixel groups includes an overflow region configured to move electrical charges between adjacent photodiodes.