Focus Detection Error Correction via Pupil Area Signal Adjustment
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Solution Overview
Problem
The existing focus detection apparatuses face accuracy issues due to shape differences between focus detection signals caused by varying pupil areas, leading to inconsistent effective baseline lengths across spatial frequency bands, which degrade focus detection precision.
Innovation Solution
A focus detection apparatus and method that corrects focus detection errors by generating and processing focus detection signals from subpixels receiving light through different pupil areas, using a two-dimensional image sensor with micro lenses and subpixels, and applying correction coefficients based on pupil intensity distributions and defocus amounts to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light shielding layer with an opening is used to divide the pupil area into different regions, then focus detection can be performed by receiving light from different pupil areas, but shape differences occur between focus detection signals from different partial pupil areas, causing focus detection accuracy to deteriorate
Solution Approach 1:
The patent changes the parameter of pupil area allocation by dynamically adjusting which pupil areas are assigned to focus detection pixels based on the imaging state. This allows the system to adapt to different shooting conditions and maintain consistent signal shapes across varying scenarios, thereby resolving the shape difference problem while preserving focus detection accuracy
Solution Approach 2:
The patent introduces dynamic adjustment of pupil area division based on imaging conditions. The control unit dynamically determines which pupil areas correspond to which focus detection pixels, making the system adaptable rather than static. This dynamic approach ensures that focus detection signals maintain consistent shapes across different shooting scenarios, solving the accuracy deterioration caused by fixed pupil division
2Adaptability or versatility
If different partial pupil areas are assigned to different focus detection pixels, then focus detection signals can be obtained from multiple spatial frequency bands, but the effective baseline length varies for each spatial frequency band, leading to focus detection errors
Solution Approach 1:
The patent dynamically changes the parameter of pupil area assignment based on the spatial frequency characteristics of the imaging state. By adjusting which pupil areas are allocated to which focus detection pixels according to the current shooting conditions, the system maintains consistent effective baseline lengths across different spatial frequency bands, thereby eliminating focus detection errors while preserving multi-band coverage capability
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
The solution enables high-accuracy focus detection by correcting errors caused by shape differences in focus detection signals, enhancing the precision of focus determination in imaging systems.
Implementation Method 1
a two-dimensional image sensor in which a micro lens is formed on each pixel
Data Source
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AI summary
[PROBLEMS] To provide a focus detection apparatus, a focus detection method, and a focus detection program, each of which can correct a focus detection error caused by a shape difference between the focus detection signals, and perform a focus detection with high accuracy. [SOLUTION MEANS] A focus detection apparatus configured to perform a focus detection using a pixel signal obtained by photoelectrically converting light passing through different pupil areas in an imaging optical system includes an acquisition means configured to acquire the pixel signal, a signal generation means configured to generate a plurality of focus detection signals corresponding to the different pupil areas using the pixel signal, and a focus detection means configured to calculate a detected defocus amount based on the plurality of focus detection signals, and to calculate a corrected defocus amount by correcting the detected defocus amount based on a phase transfer function corresponding to the different pupil areas.