Image Sensor Micro-Lens Segmentation Autofocus

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Solution Overview

Problem

Conventional image sensors with reduced pixel size face challenges in light reception uniformity and precision, leading to inaccurate autofocus and image focus due to the conventional single micro-lens arrangement over groups of autofocus sensor units, which results in insufficient light reception and misalignment issues.

Innovation Solution

The innovative arrangement involves multiple micro-lenses with varying gaps over each autofocus sensor unit within a group and between groups, along with a top film conformally coated on the micro-lenses, to ensure uniform light reception and enhance autofocus functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If pixel size is reduced to increase resolution, then the number of pixels increases, but light reception uniformity and precision deteriorate

Engineering Contradiction:

Improvenumber of pixelsVSAvoidlight reception uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent divides the single micro-lens structure into multiple micro-lenses corresponding to each sensing portion within the autofocus sensor unit. This segmentation allows each sensing portion to have its own dedicated micro-lens, ensuring uniform light reception across all pixels even as pixel size is reduced and density increases.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces different gap configurations between micro-lenses based on their location: gaps between micro-lenses within the same autofocus sensor unit have a first depth, while gaps between micro-lenses of different autofocus sensor units have a second depth (larger than the first). This local differentiation optimizes light reception for each specific sensing portion while maintaining overall uniformity.

Inventive Principle:

Principle #3Local quality

2Device complexity

If a single micro-lens is used over groups of autofocus sensor units, then device complexity is reduced, but light reception sufficiency and alignment precision deteriorate

Engineering Contradiction:

Improvemicro-lens arrangementVSAvoidautofocus accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Instead of using a single micro-lens covering multiple autofocus sensor units, the patent segments the micro-lens structure so that each sensing portion has its own micro-lens. This ensures that light from each sensing portion is properly focused, maintaining autofocus accuracy while accommodating reduced pixel sizes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different gap depths between micro-lenses based on their spatial relationships: micro-lenses within the same autofocus sensor unit have smaller gaps (first depth) for precise light direction detection, while micro-lenses between different autofocus sensor units have larger gaps (second depth) to prevent light interference. This local quality differentiation ensures reliable autofocus function.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If pixel size is reduced, then image sensor resolution increases, but alignment precision and signal reading accuracy deteriorate

Engineering Contradiction:

Improvepixel densityVSAvoidsignal reading accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent assigns a dedicated micro-lens to each sensing portion, ensuring that even as pixel size is reduced and density increases, each pixel maintains proper light focusing capability. This prevents signal reading errors that would occur with a single shared micro-lens structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent optimizes light reception for each sensing portion by configuring micro-lens gaps locally: smaller gaps within autofocus sensor units enhance precision for that unit's sensing portions, while larger gaps between units prevent cross-interference. This ensures accurate signal readings across the entire sensor array.

Inventive Principle:

Principle #3Local quality

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 solution ensures each sensing portion receives sufficient light, maintaining accurate signal readings and improving the image sensor's ability to track and detect light direction, even in cases of process overlay, thereby enhancing the overall autofocus function.

Implementation Method 1

reflowing the hard mask pattern into a plurality of dome shapes; transferring the plurality of dome shapes into the micro-lens material layer to form a plurality of micro-lenses

Methodology Applied

Scientific EffectReflow:

Implementation Method 2

forming a top film conformally on the plurality of micro-lenses

Methodology Applied

Scientific EffectConformal deposition: Deposition (physical)

Data Source

PatentUS20230102094A1Image sensor

Publication Date: 2023.03.30 VISERA TECH CO LTD

AI summary

An image sensor includes a plurality of groups of autofocus sensor units. Each of the groups of autofocus sensor units includes a plurality of sensing portions, a color filter layer disposed on the sensing portions, and a plurality of micro-lenses disposed on the color filter layer and correspondingly above the plurality of sensing portions. The image sensor includes a top film disposed conformally on the plurality of micro-lenses. A joint seam between the micro-lenses within one of the groups of autofocus sensor units has a first depth. A gap between the micro-lenses of the plurality of groups of autofocus sensor units has a second depth. The second depth is larger than the first depth.