Focus Detection Device Color-Specific Defocus Calculation
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Solution Overview
Problem
Focus detection results across different colors in existing focus detection devices often do not match, leading to inconsistencies in defocus amount calculations.
Innovation Solution
A focus detection device is designed with pixels having different color filters (red, green, and blue) that use specific conversion coefficients for each color to calculate defocus amounts, allowing for accurate focus detection by selecting signals based on contrast or light source color, and adjusting for color-specific diffraction effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If focus detection is executed for multiple colors using the same conversion coefficient, then the device complexity is reduced, but the measurement precision of defocus amount deteriorates due to color-specific diffraction effects
Solution Approach 1:
The patent applies local quality by assigning different conversion coefficients to different colors (wavelengths). Each color channel (red, green, blue) has its own optimized conversion coefficient that accounts for its specific diffraction characteristics. This allows the system to maintain high measurement precision for each color while managing complexity through organized storage and selection of color-specific coefficients.
Solution Approach 2:
The patent changes the parameter of conversion coefficient based on the wavelength/color of light being measured. By selecting appropriate conversion coefficients corresponding to different wavelengths, the system adapts to the physical properties of different colors of light, particularly their different diffraction effects, thereby improving defocus amount calculation accuracy across the visible spectrum.
2Ease of operation
If a single conversion coefficient is used for all colors, then the ease of operation is improved, but the reliability of focus detection deteriorates due to inconsistent defocus amounts across colors
Solution Approach 1:
The patent implements a dynamic selection mechanism that automatically chooses the appropriate conversion coefficient based on the detected light wavelength or color information. This dynamic approach maintains ease of operation by automating the coefficient selection process, while simultaneously improving reliability by ensuring that the most appropriate coefficient is used for each specific color channel.
Solution Approach 2:
The system uses feedback from color detection (wavelength identification) to select the appropriate conversion coefficient. By detecting the color characteristics of the incoming light and using this information to guide coefficient selection, the system ensures consistent and reliable focus detection results across different colors without requiring manual intervention.
3Adaptability or versatility
If color filters are disposed at focus detection pixels, then the adaptability to different light conditions is improved, but the object-generated harmful factors increase due to color-specific diffraction effects causing mismatched defocus amounts
Solution Approach 1:
The patent converts the harmful effect of color-specific diffraction into a beneficial feature by using it as the basis for selecting appropriate conversion coefficients. Instead of treating the different diffraction patterns of various colors as problems to be eliminated, the system embraces them by implementing wavelength-dependent conversion coefficients that optimize focus detection for each color channel, thereby improving overall adaptability to different light conditions.
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 enables highly accurate focus detection that is unaffected by color differences, ensuring consistent results across various light conditions.
Implementation Method 1
a pair of photoelectric conversion units disposed to the rear of the micro-lens, via which a pair of image signals corresponding to a pair of images formed with a pair of focus detection light fluxes passing through an optical system are generated
Data Source
AI summary
A focus detection device includes: a plurality of first pixels having first color filters, via which a pair of first signals, to be used for split-pupil phase detection, are output; a plurality of second pixels having second color filters, via which a pair of second signals, to be used for the split-pupil phase detection, are output; a phase difference detection unit that detects a phase difference manifested by the first signals or a phase difference manifested by the second signals; and a defocus amount calculation unit that calculates a defocus amount by using a first conversion coefficient corresponding to the first color when the phase difference detection unit has detected the phase difference manifested by the first signals and by using a second conversion coefficient corresponding to the second color when the phase difference detection unit has detected the phase difference manifested by the second signals.