Focus Detection Apparatus Chromatic Aberration Weighting
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Solution Overview
Problem
Phase difference AF methods in image capturing apparatuses face challenges in accurately correcting focus detection errors caused by chromatic aberration of magnification, which is complicated by manufacturing variations and color shading differences in image sensors.
Innovation Solution
A focus detection apparatus and method that utilizes color filters and photoelectric conversion units in an image sensor to generate weighted focus detection signals based on chromatic aberration characteristics of the imaging optical system, allowing for precise focus detection by adjusting weights for signals from different spectral sensitivity pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase difference AF uses signals from multiple colors to perform focus detection, then focus detection speed is improved, but focus detection precision deteriorates due to chromatic aberration of magnification
Solution Approach 1:
The patent changes the parameter of signal weighting by dynamically adjusting addition coefficients for different color signals based on chromatic aberration characteristics. This allows the system to adaptively compensate for chromatic aberration effects while maintaining the speed benefits of multi-color phase difference detection
Solution Approach 2:
The patent implements feedback by using detected chromatic aberration characteristics to adjust the addition coefficients for color signal combination. This closed-loop approach continuously optimizes focus detection precision by compensating for chromatic aberration based on actual optical system performance
2Measurement precision
If correction values are adjusted based on chromatic aberration characteristics, then focus detection precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by adjusting addition coefficients specifically for color signals affected by chromatic aberration of magnification, rather than uniformly processing all signals. This targeted approach improves precision while minimizing additional processing complexity by focusing computational resources only where needed
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 effectively suppresses focus detection errors due to chromatic aberration of magnification, enabling high-precision focus detection by accurately accounting for chromatic aberration and manufacturing variations.
Implementation Method 1
a plurality of photoelectric conversion portions for each of a plurality of microlenses, that performs photoelectric conversion on light incident on the image sensor via an imaging optical system and outputs electric signals
Data Source
AI summary
A focus detection apparatus that performs phase difference focus detection based on signals of a plurality of colors obtained from an image sensor, which is covered by color filters of the plurality of colors, that performs photoelectric conversion on light incident on the image sensor via an imaging optical system and outputs electric signals, the apparatus comprising: an acquisition unit that acquires an addition coefficient indicating weights to be applied to the signals of the plurality of colors on the basis of characteristic of chromatic aberration of magnification of the imaging optical system; a generation unit that generates a pair of focus detection signals by performing weighted addition on the signals of the plurality of colors using the addition coefficient; and a detection unit that detects an image shift amount between the pair of focus detection signals.