Image Sensor Focus Detection Parallax Signal Normalization
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Solution Overview
Problem
Existing image capturing apparatuses face challenges in maintaining high image quality and accurate focus detection during continuous still image shooting, as exposure settings for still images and live view shooting often differ, leading to flicker and blur issues due to slight luminance or aperture changes.
Innovation Solution
An image capturing apparatus equipped with a processor-controlled image sensor featuring focus detection pixels that output parallax signals from different pupil regions, allowing for exposure control optimization and focus state detection, along with an estimator normalizing evaluation values to assess focus reliability, ensuring consistent image quality and focus accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exposure control values are set differently for still image shooting and live view shooting to optimize each mode, then shooting performance for each mode is improved, but flicker and blur occur in live view images due to luminance and aperture changes
Solution Approach 1:
The system dynamically changes exposure control parameters (shutter speed, aperture, gain) based on the shooting mode. For still image shooting, parameters are optimized for high-quality capture, while for live view shooting, parameters are adjusted to prevent flicker and maintain stable display, resolving the contradiction between mode-specific optimization and visual stability
Solution Approach 2:
The exposure control values are made dynamic rather than static, allowing the system to adapt parameters in real-time based on the current shooting mode and scene conditions. This enables the system to switch between still image and live view modes without experiencing flicker or quality degradation
2Speed
If high-speed AF is implemented by alternately performing still image shooting and live view shooting, then focusing speed is improved, but alternating display causes flicker in the live view image
Solution Approach 1:
The system implements periodic switching between still image shooting and live view shooting modes at optimized intervals. This periodic action enables high-speed autofocus while maintaining stable live view display by carefully timing the alternation to minimize visual disruption and flicker
Solution Approach 2:
The system maintains continuous focus detection and image capture operations by seamlessly alternating between still image and live view modes. The useful action of focus detection continues uninterrupted while the display alternates in a controlled manner that preserves image stability
3Manufacturing precision
If aperture is changed to optimize exposure for still image shooting, then still image quality is improved, but blur alternation is observed in out-of-focus areas causing large flicker
Solution Approach 1:
The system applies different exposure strategies to different shooting modes. For still image shooting, aperture is optimized for maximum quality, while for live view shooting, aperture settings are specifically chosen to minimize flicker and blur alternation, allowing each mode to have its own optimized parameters without interfering with the other
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-quality live view images and accurate focus detection by optimizing exposure settings and normalizing focus reliability, reducing flicker and blur caused by exposure changes, thereby enhancing the overall shooting experience.
Implementation Method 1
an image sensor that includes a plurality of focus detection pixels capable of outputting a pair of signals having parallax based on light fluxes that have passed through different pupil regions of an imaging optical system
Data Source
AI summary
An image capturing apparatus comprising: an image sensor that includes a plurality of focus detection pixels capable of outputting a pair of signals to be used for focus detection; a setter that sets an exposure control value based on a result of photometry; a controller that controls to perform image shooting by controlling exposure based on the exposure control value set by the setter; a detector that detects a focus state based on the pair of signals read out from the plurality of focus detecting pixels under control of the controller; and an estimator that estimates reliability of the focus state detected by the detector by normalizing an evaluation value obtained at a time of detecting the focus state by the detector in a case where the image shooting is performed using the exposure control value set by the setter.