Focus Adjustment Device Phase Difference Detection

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Solution Overview

Problem

Existing focus adjustment devices struggle with accurately determining true image shift amounts, especially when dealing with subjects having periodic patterns, leading to false focusing and prolonged computational processing times, which hinders high-speed consecutive shooting and precision.

Innovation Solution

A focus adjustment device that sets a first and second focus detection region, with the second region being narrower than the first, performs phase difference detection, and determines periodicity to select the closest phase difference for focus adjustment, allowing for rapid and reliable focusing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a wide focus detection region is used to include all image plane regions, then the effect of periodic patterns is reduced, but computational processing time increases and arithmetic circuit scale increases

Engineering Contradiction:

Improvefocus detection accuracyVSAvoidcomputational processing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The image plane is divided into multiple focus detection regions, allowing selective processing of specific areas rather than the entire image plane. This segmentation reduces the computational burden while maintaining focus detection accuracy by concentrating processing resources on relevant regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different focus detection regions are assigned different processing priorities and methodologies based on their local characteristics. Regions containing periodic patterns are handled with specialized algorithms, while other regions use standard processing, optimizing overall computational efficiency.

Inventive Principle:

Principle #3Local quality

2Reliability

If a wide focus detection region is used, then the effect of periodic patterns is reduced, but the scale of arithmetic circuit increases

Engineering Contradiction:

Improvefocus detection accuracyVSAvoidarithmetic circuit scale

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The arithmetic circuit is divided into multiple processing units, each handling specific focus detection regions. This modular approach reduces the scale of individual circuits while maintaining overall processing capability through parallel operation of multiple smaller units.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A control unit acts as an intermediary that coordinates between multiple processing units and manages data flow. This intermediary structure allows complex focus detection tasks to be distributed across simpler processing units, reducing individual circuit scale while maintaining system capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple focus candidate points are calculated for periodic pattern subjects, then comprehensive coverage is achieved, but true focus target position cannot be detected and false focusing arises

Engineering Contradiction:

Improvecoverage of focus candidatesVSAvoidfocus target position detection

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system uses feedback mechanisms to evaluate multiple focus candidate points and select the true focus position. By analyzing correlation values and comparing results across different focus detection regions, the system can identify the correct focus point even when periodic patterns generate multiple candidates.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Instead of processing all possible focus candidates equally, the system performs partial processing on selected candidates based on preliminary evaluation. This approach reduces computational load while ensuring the true focus point is identified through targeted analysis of the most promising candidates.

Inventive Principle:

Principle #16Partial or excessive action

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

Enables high-speed determination of true image shift amounts and reliable focusing even with periodic patterns, reducing computational processing time and maintaining focus during high-speed shooting.

Implementation Method 1

generates image data by receiving light of a subject image that has been subjected to pupil division by means of a photographing lens

Methodology Applied

Scientific EffectPupil division:

Data Source

PatentUS10750079B2Focus adjustment device and focus adjustment method

Publication Date: 2020.08.18 OLYMPUS CORPORATION(JP)

AI summary

A focus adjustment device, comprising a processor having a focus region setting section, a focus detection section, a determination section and a control section, wherein the focus detection region setting section sets a first focus detection region, and a second focus detection region, that is contained in the first focus detection region and that is narrower than the first focus detection region, in an imaging region, the control section, when it is determined that that there is not a periodicity-containing subject for the first focus detection region, and it is determined that there is a periodicity-containing subject for the second focus detection region, performs a focus adjustment operation by selecting a phase difference that is closest to a phase difference that has been detected for the first focus detection region, among a plurality of phase differences that have been detected for the second focus detection region.