Focus Detection Apparatus Saturation Handling Phase Difference
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Solution Overview
Problem
Conventional focus detection apparatuses using phase difference methods face challenges in achieving high accuracy due to signal saturation in divided photoelectric conversion devices, leading to charge leakage and deterioration of phase difference images, and difficulties in recognizing original signals for luminance component calculation.
Innovation Solution
A focus detection apparatus that includes saturation detectors for each pixel, generates luminance signals after detecting saturation, and performs correlation calculations based on these signals to improve focus detection accuracy by considering saturation levels and maintaining signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If divided PDs are used for phase difference focus detection, then focus detection capability is improved, but signal saturation causes charge leakage to adjacent PDs which deteriorates detection accuracy
Solution Approach 1:
The patent applies preliminary action by detecting saturation in the first signal before performing focus detection. The saturation detection unit identifies whether the first signal from the first divided PD is saturated, and this information is used to selectively process or discard the corresponding phase difference image data, preventing saturated data from degrading the correlation calculation results.
Solution Approach 2:
The patent extracts and removes saturated signal data from the focus detection process. By identifying saturation in individual divided PD signals and excluding their corresponding phase difference image data from the correlation calculation, the system separates harmful saturated data from useful unsaturated data, maintaining detection accuracy.
2Reliability
If luminance component signals are calculated from divided PD signals for saturation detection, then saturation can be detected, but the original signal information is lost making accurate focus detection difficult
Solution Approach 1:
The patent creates a copy of the first signal specifically for saturation detection purposes. The saturation detection unit receives a copy of the first signal to determine saturation status, while the original first signal is preserved and used in the correlation calculation for focus detection, thus maintaining all original information.
Solution Approach 2:
The patent segments the signal processing into separate functional paths: one path for saturation detection (using the first signal) and another path for focus detection (using both first and second signals). This segmentation allows saturation detection without compromising the integrity of signals needed for accurate focus determination.
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 enhances focus detection accuracy by detecting saturation in each pixel before the focus detection process, allowing for precise correlation calculations and improved image quality by preventing charge leakage and maintaining signal integrity.
Implementation Method 1
a first pixel and a second pixel sharing one micro lens of a solid-state image pickup element
Data Source
AI summary
A focus detection apparatus performs focus detection of a phase difference method by using signals from an image pickup element including a first pixel and a second pixel sharing one micro lens, and the focus detection apparatus includes a first saturation detector configured to detect saturation of a first signal obtained from the first pixel, a second saturation detector configured to detect saturation of a second signal obtained from the second pixel, a luminance generating portion configured to generate luminance signals of the first signal and the second signal after detecting the saturations of the first signal and the second signal are detected, and a processor configured to perform a correlation calculation based on the luminance signals.