Focusing Control Device Phase Difference Autofocus Correlation
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Solution Overview
Problem
The phase difference auto focus (AF) method in imaging devices often faces challenges in accurately determining the minimum correlation value due to inflection points and noise, leading to potential errors in focusing control, especially with periodic patterns and multiple candidates for the minimum value.
Innovation Solution
A focusing control device and method that utilizes a sensor with first and second signal detection sections to calculate correlation values for different shift amounts, then divides the correlation graph into areas to obtain accumulative values, narrowing the search range for the minimum value based on these accumulative values, thereby improving focusing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference detection is performed using correlation calculation with pixel row data, then focusing control can be achieved, but multiple inflection points and noise cause erroneous determination of the minimum correlation value
Solution Approach 1:
The patent divides the pixel rows into multiple groups (first pixel rows and second pixel rows) and performs correlation calculation between corresponding groups. By segmenting the detection area and using multiple groups of pixels, the patent reduces the impact of noise and inflection points on the minimum correlation value determination, thereby improving both measurement precision and reliability of focusing control.
2Measurement precision
If the entire correlation graph is searched for the minimum value, then the most accurate focus can be found, but processing time and computational load increase
Solution Approach 1:
The patent performs preliminary correlation calculation between multiple groups of pixel rows to obtain multiple correlation values before determining the final minimum value. This preliminary action of using multiple pixel groups provides a more robust basis for minimum value determination, reducing the need for extensive searching and thereby reducing processing time while maintaining accuracy.
Solution Approach 2:
The patent uses the correlation values obtained from multiple pixel row groups as feedback to determine the minimum correlation value more reliably. By comparing multiple correlation values from different pixel groups, the system can identify the true minimum value more quickly and accurately, reducing both processing time and computational load.
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 enhances focusing precision by accurately determining the minimum correlation value, reducing the risk of errors and processing load, and enabling faster autofocus operations.
Implementation Method 1
a sensor in which a plurality of first signal detection sections that receive one of pair of luminous fluxes passing through different portions arranged in one direction of a pupil region of an imaging optical system including a focus lens and detect signals and a plurality of second signal detection sections that receive the other one of the pair of luminous fluxes and detect signals are formed
Data Source
AI summary
A focusing control device includes: a sensor that has a focus detection area in which a plurality of first signal detection sections which receives one of a pair of luminous fluxes passing through different portions arranged in one direction of a pupil region of an imaging optical system including a focus lens and detects signals and a plurality of second signal detection sections which receives other one of the pair of luminous fluxes and detects signals are formed; and a processor, configured to obtain correlation values, obtain an accumulative value of the correlation values included in each of a plurality of division areas obtained by dividing a graph of the correlation values in which shift amounts are represented on a first axis in a direction of the first axis, and perform focusing control by controlling the focus lens based on the accumulative value obtained.