Phase Difference Pixel Array for Autofocus Accuracy

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Solution Overview

Problem

The image plane phase difference method for focus detection lacks accuracy due to mismatched exit pupil distances and phase difference characteristics of phase difference detection pixels, leading to uneven light reception and reduced autofocus precision.

Innovation Solution

A signal processing device and method that acquires distance measurement information by adding outputs from multiple phase difference detection pixels with varying phase difference characteristics, arranged on an imaging element, to improve focus detection accuracy across different exit pupil distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If phase difference detection pixels with fixed phase difference characteristics are used, then the device structure is simple, but focus detection accuracy deteriorates when exit pupil distances vary

Engineering Contradiction:

Improvefocus detection accuracyVSAvoidimaging element structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The imaging element is segmented into multiple types of phase difference detection pixels, each with different phase difference characteristics corresponding to different exit pupil distances. This segmentation allows the system to handle varying exit pupil distances by selecting or combining appropriate pixel types, thereby maintaining focus detection accuracy without requiring a completely complex reconfigurable structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The imaging element is designed with multi-functionality by incorporating multiple types of phase difference detection pixels that can handle different exit pupil distances. This universal design allows the same imaging element to work with interchangeable lenses having different exit pupil distances, improving focus detection accuracy across various lens configurations without requiring separate dedicated sensors for each lens type.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If single type of phase difference detection pixel is used, then manufacturing is simple, but focus detection accuracy deteriorates due to uneven light reception

Engineering Contradiction:

Improvefocus detection accuracyVSAvoidimaging element fabrication

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Different regions or zones of the imaging element are assigned different types of phase difference detection pixels with specific phase difference characteristics optimized for particular exit pupil distance ranges. This local quality approach ensures that each pixel type operates in its optimal performance range, improving focus detection accuracy while maintaining a systematic manufacturing process that can be implemented through structured fabrication techniques.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If phase difference detection pixels are optimized for specific exit pupil distance, then measurement precision is high for that distance, but adaptability to interchangeable lenses deteriorates

Engineering Contradiction:

Improvefocus detection accuracyVSAvoidlens compatibility

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system changes the parameter of phase difference characteristics by incorporating multiple types of phase difference detection pixels, each optimized for different exit pupil distances. This parameter variation allows the imaging element to adapt to interchangeable lenses with different exit pupil distances, maintaining high focus detection accuracy across various lens types through selective use or combination of appropriate pixel types.

Inventive Principle:

Principle #35Parameter changes

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 focus detection accuracy by averaging outputs from phase difference detection pixels with distinct characteristics, ensuring precise autofocus even with interchangeable lenses having different exit pupil distances, thus preventing degradation in image quality and accuracy.

Implementation Method 1

phase difference detection pixels for detecting the focus is arranged on the same imaging element

Methodology Applied

Scientific EffectPhase difference detection:

Implementation Method 2

outputs of a plurality of phase difference detection pixels supplied from an imaging element

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS11394866B2Signal processing device, imaging device, signal processing meihod and program

Publication Date: 2022.07.19 SONY GROUP CORP

AI summary

Provided is a signal processing device including a control unit that acquires distance measurement information on the basis of an addition value obtained by adding together outputs of a plurality of phase difference detection pixels supplied from an imaging element in which the plurality of phase difference detection pixels different in phase difference characteristic is arranged.