Multifocal Lens Focusing Control for High-Speed Image Capture

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Solution Overview

Problem

Conventional multifocal lens imaging technologies struggle to achieve maximum focus performance due to blur within the allowable circle of confusion across the entire depth of field, especially when trying to focus on moving subjects or utilizing the varying focal lengths and depth of field characteristics of multifocal lenses effectively.

Innovation Solution

The imaging method controls the focusing state by selectively using different regions of a multifocal lens with varying focal lengths to quickly and accurately focus on a main subject, allowing for high-speed focusing and high-image-quality capture, while also recording image and focusing information for user selection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If convolution processing or restoration processing is performed on images obtained by a multifocal lens, then an in-focus image can be obtained to some extent, but the lens cannot be focused to maximum performance and blur occurs across the entire depth of field

Engineering Contradiction:
Improvefocus accuracyVSAvoidimage quality
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The imaging device divides the multifocal lens into multiple regions (first region, second region, third region) with different focal lengths, and selectively uses appropriate regions based on subject distance. This segmentation allows each region to be optimized for specific focusing scenarios, achieving maximum lens performance without blur across the entire depth of field.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different lens regions and adjusting focusing states based on detected subject distance. Rather than using a fixed processing approach, the system adapts by selecting which region to use (first region for close subjects, second region for medium distance, third region for far subjects), enabling optimal focus accuracy and image quality for each scenario.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple camera modules with different focal lengths are used to capture images, then a multifocal image can be obtained, but the system becomes complex and upsized

Engineering Contradiction:
Improvefocal length coverageVSAvoidsystem structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A single multifocal lens is designed to perform multiple functions by providing different focal lengths through its different regions. The first region provides short focal length for close subjects, the second region provides medium focal length, and the third region provides long focal length for distant subjects. This makes one lens universal, replacing what would traditionally require multiple separate camera modules.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

Multiple focal length capabilities are merged into a single multifocal lens structure. Instead of having separate camera modules for different focal lengths, the patent combines all focal length variations into one lens with multiple regions, each having different optical characteristics. This merging simplifies the system structure while maintaining versatile focal length coverage.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a deep depth of focus is set or restoration processing is performed, then an in-focus image can be obtained in a wide range, but accurate focusing on moving subjects is difficult

Engineering Contradiction:
Improvefocus coverage rangeVSAvoidfocusing speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The system dynamically adjusts the focusing state by detecting subject distance and switching between different lens regions. When a moving subject is detected, the system quickly transitions to the appropriate region (e.g., first region for close subjects, third region for distant subjects) rather than relying on deep depth of focus. This dynamic adaptation enables both wide focus coverage and fast focusing speed on moving subjects.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system performs preliminary distance detection and pre-selects the appropriate lens region before capturing the image. By detecting subject distance in advance and preparing the correct region (first, second, or third region), the system ensures accurate focusing on moving subjects without needing to rely on deep depth of focus or post-capture restoration processing.

Inventive Principle:
Principle #10Preliminary 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

This approach enables the capture of desired images that take advantage of the multifocal lens's characteristics, allowing for rapid focusing and high-quality images that maximize lens performance, with the ability to select images based on focus speed, quality, and region.

Implementation Method 1

a multifocal lens having a plurality of regions, the plurality of regions having different focal lengths

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2772782B1Imaging method and image processing method, program using same, recording medium, and imaging device
Publication Date: 2017.04.12 FUJIFILM CORP
  • EP2772782B1 patent drawingFigure 1
  • EP2772782B1 patent drawingFigure 2
  • EP2772782B1 patent drawingFigure 3

AI summary

An imaging method according to an aspect of the present invention is an imaging method using a multifocal lens having a plurality of regions, the plurality of regions having different focal lengths, and the imaging method includes a focusing state control step of controlling a focusing state of the multifocal lens, and an imaging step of obtaining an image of a subject in the controlled focusing state. Since the focusing state of the multifocal lens having a plurality of focal lengths is controlled to obtain an image of the subject, a desired image, such as an accurately-focused image and an image focused at high speed, can be obtained by taking advantage of the characteristics of the multifocal lens. In this imaging method, the image may be obtained by controlling the focusing state according to a relation between a depth of field of the multifocal lens and the width of a distance distribution of the subject, or the image may be obtained by controlling the focusing state in response to the picture-taking instruction so that a main subject is focuses via any of the plurality of regions.