Focus Detection Apparatus Aberration Correction
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Solution Overview
Problem
Conventional focus detection methods in image capturing apparatuses suffer from errors due to differences in image resolution and optical aberrations, which are not adequately corrected by existing AF systems that do not account for viewing environments.
Innovation Solution
A focus detection apparatus and method that includes a focus detection unit, aberration information acquisition, and a correction unit to adjust the in-focus position based on aberration information and viewing conditions, using a display unit's image signal to calculate and apply a correction value for precise focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional focus detection methods (contrast AF or phase difference AF) are used, then focus detection can be performed using optical images, but focus detection errors arise due to differences in image resolution and optical aberrations
Solution Approach 1:
The patent changes the parameter of focus detection position by introducing a correction value that adjusts the detected in-focus position based on aberration information and viewing conditions. This parameter adjustment compensates for systematic errors caused by optical aberrations and resolution differences between capture and display, thereby improving focus detection accuracy without changing the fundamental AF method
Solution Approach 2:
The patent implements a feedback mechanism where aberration information about the imaging optical system is acquired and used to calculate a correction value. This correction value is then applied to adjust the focus detection position, creating a closed-loop system that continuously compensates for aberration-induced errors and enhances measurement precision
2Device complexity
If focus detection is performed without considering viewing environment, then the detection process is simple, but focus detection error cannot be corrected to a sufficient extent
Solution Approach 1:
The patent performs preliminary action by acquiring aberration information about the imaging optical system before focus detection and adjustment. This pre-acquired information is stored and later used to calculate the correction value, allowing the system to compensate for aberrations in advance rather than requiring complex real-time adjustments during focus detection
Solution Approach 2:
The patent introduces dynamics by making the focus detection position adjustable based on viewing conditions. The correction value is calculated considering factors such as display device characteristics and viewing environment, allowing the system to adaptively adjust the focus position dynamically rather than using a fixed detection position, thereby improving accuracy without excessive complexity
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 solution effectively reduces focus detection errors by accounting for both image capturing and viewing conditions, providing more accurate focus adjustment and improving the precision of focus detection.
Implementation Method 1
an image sensor that photoelectrically converts light that has entered via an imaging optical system into an image signal
Data Source
AI summary
A focus detection apparatus comprising: a focus detection unit that detects an in-focus position using an image signal obtained by an image sensor photoelectrically converting light that has entered via an imaging optical system; a first acquisition unit that acquires aberration information of the imaging optical system; a generating unit that generates a recording image using the image signal; a calculation unit that calculates, on the basis of the aberration information, a correction value for correcting a difference between the in-focus position detected by the focus detection unit and a position to be focused on in the recording image; and a correction unit that corrects the in-focus position using the correction value. The calculation unit calculates the correction value on the basis of information of a display unit that displays an image based on the image signal.