Scheimpflug Autofocus Aligning Rotation Axis

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Solution Overview

Problem

Existing image-capturing apparatuses require manual focus adjustment, which is cumbersome, and fail to achieve desired depth-of-field expansion when the object does not overlap the image-capturing plane's rotation axis, limiting the effectiveness of tilt control in capturing images with deep depth of field, especially under low illuminance conditions.

Innovation Solution

An image-capturing apparatus that automatically detects and adjusts the focus area based on contrast evaluation values and object distance information, ensuring the focus area aligns with the image sensor rotation axis, thereby enabling tilt control to deepen the depth of field without user intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tilt control is performed by rotating the image-capturing plane, then the depth of field is deepened, but manual focus adjustment is required which increases operation complexity

Engineering Contradiction:
Improvedepth of fieldVSAvoidfocus adjustment
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system performs automatic focus adjustment by detecting the rotation axis position and autonomously calculating the optimal focus area, eliminating the need for manual user intervention in focus setting while maintaining the deepened depth of field effect from tilt control

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical focus adjustment with an automated optical detection and control system that uses image processing to detect the rotation axis and automatically sets the focus area, substituting human operation with computational algorithms

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If focus is adjusted on an object not overlapping the rotation axis, then the object is in focus, but the depth-of-field expansion effect cannot be achieved

Engineering Contradiction:
Improvefocus accuracyVSAvoiddepth of field effect
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system detects the rotation axis position from captured images and uses this feedback information to automatically calculate and adjust the focus area to the correct position, ensuring both accurate focus and proper depth of field expansion effect are achieved simultaneously

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary detection of the rotation axis position and pre-calculates the optimal focus area before capturing the final image, ensuring the focus is correctly positioned to achieve the desired depth of field effect without requiring trial-and-error adjustments

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

Facilitates easy and accurate focus adjustment suitable for tilt control, ensuring the entire image area is in focus and achieving a desired depth-of-field expansion effect, even when the object does not overlap the image-capturing plane's rotation axis, improving image quality under various lighting conditions.

Implementation Method 1

an image-capturing optical system including an image-capturing optical unit and an image sensor

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3684046B1Autofocus in an image-capturing apparatus operating using the scheimpflug principle
Publication Date: 2022.12.07 CANON KK
  • EP3684046B1 patent drawingFigure 1
  • EP3684046B1 patent drawingFigure 2A~2B
  • EP3684046B1 patent drawingFigure 3~4

AI summary

An image-capturing apparatus (100) includes a controller (115) configured to perform tilt control where an image sensor (106) is tilted about a rotation axis with respect to a plane orthogonal to an optical axis of an image-capturing optical system, a focus position determiner (115) configured to determine a position of a focus lens(102), a first area detector (119) configured to detect a first area corresponding to the rotation axis in a captured image, and a second area detector (113) configured to detect a second area which is an area to be focused by the tilt control, wherein the focus position determiner determines a third area where the first and second areas overlap as a focus position before the tilt control, and the controller performs the tilt control after the position of the focus lens is adjusted so that the third area is in focus.