Asymmetrical Pixel Pair Depth Sensing in Image Sensors

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Solution Overview

Problem

Conventional image sensors face challenges in capturing images with acceptable detail, particularly when objects are positioned in shadows or at different distances, leading to blurred images due to limited depth of field and dynamic range.

Innovation Solution

The image sensor employs asymmetrical photo detector pairs with a light shield partially blocking light on each detector, allowing for depth of field information determination and operation in charge summing, high dynamic range, and depth of field modes, using a color filter array to filter light wavelengths and improve signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a camera focuses on an object at a specific distance, then that object appears sharp in the image, but objects at other distances become blurred

Engineering Contradiction:

Improvefocus accuracyVSAvoiddepth of field information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

Each pixel is divided into multiple photo detectors (e.g., first and second photo detectors) that independently capture light from different directions. This segmentation allows the system to obtain depth information from multiple focal planes simultaneously, resolving the contradiction between sharp focus at one distance and information loss about other distances

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs asymmetrical arrangements of photo detectors within pixels, where detectors are positioned and configured to preferentially receive light from different angular directions. This asymmetry enables the system to distinguish depth information by comparing signals from detectors with different directional sensitivities, allowing focus determination while preserving depth of field information

Inventive Principle:

Principle #4Asymmetry

2Adaptability or versatility

If objects are positioned in shadows or at different distances, then the scene complexity increases, but the image quality deteriorates with blurred objects

Engineering Contradiction:

Improvescene handling capabilityVSAvoidimage sharpness

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The image sensor performs multiple functions simultaneously: it captures standard images for normal viewing, determines focus settings by analyzing photo detector signal ratios, and extracts depth of field information. This multi-functionality allows the system to handle complex scenes with objects at various distances and lighting conditions while maintaining image quality through intelligent focus adjustment

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If conventional image sensors are used, then the device complexity remains low, but the depth of field information and focus determination capability are insufficient

Engineering Contradiction:

Improvefocus setting determinationVSAvoidsensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines depth sensing functionality with standard image capture by integrating multiple photo detectors within each pixel structure. The same pixel array that captures images also determines focus settings by comparing signals from different photo detectors, eliminating the need for separate depth sensing hardware and reducing overall device complexity while improving focus determination precision

Inventive Principle:

Principle #5Merging (Combining)

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 enables better focus setting determination, enhanced image detail in both bright and dark areas, and improved depth of field information, effectively addressing the limitations of conventional image sensors.

Implementation Method 1

A light shield is disposed over a portion of two photo detectors to only partially block light incident on the two photo detectors

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 2

a color filter array disposed over the plurality of photo detectors. The color filter array includes a plurality of filter elements and the filter elements disposed over the two photo detectors can filter light wavelengths representing the same color or different colors

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

an imaging area within an image sensor that includes a plurality of photo detectors

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS10284769B2Image sensor with in-pixel depth sensing

Publication Date: 2019.05.07 APPLE INC

AI summary

An imaging area in an image sensor includes a plurality of photo detectors. A light shield is disposed over a portion of two photo detectors to partially block light incident on the two photo detectors. The two photo detectors and the light shield combine to form an asymmetrical pixel pair. The two photo detectors in the asymmetrical pixel pair can be two adjacent photo detectors. The light shield can be disposed over contiguous portions of the two adjacent photo detectors. A color filter array can be disposed over the plurality of photo detectors. The filter elements disposed over the two photo detectors can filter light representing the same color or different colors.