Split-Pixel Imaging Signal Processing for Saturation Handling
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Solution Overview
Problem
Existing imaging apparatuses with photodiode (PD) split pixels face accuracy issues in focus detection due to signal overflow, leading to imbalanced output values that hinder precise defocus amount determination.
Innovation Solution
The imaging apparatus employs a saturation handling process to correct output values by calculating differences between predicted and actual values, accounting for overflow in PD pixels, and includes a control section to determine the in-focus state, using lens information for accurate autofocus control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PD split pixel is used to detect focus by reading out multiple image signals with pupil division, then focus detection capability is provided, but signal overflow occurs in one of the PD pixels causing imbalance in output values and inaccurate defocus amount determination
Solution Approach 1:
The patent applies preliminary action by predicting the output values of PD pixels before saturation occurs. The signal processing section calculates predicted output values based on light receiving angle characteristics and lens information, then uses these predictions to correct saturated signals. This preliminary prediction mechanism allows the system to anticipate and compensate for saturation effects, maintaining accurate focus detection even when overflow occurs in one of the PD pixels.
Solution Approach 2:
The patent implements feedback by using the difference between predicted output values and actual saturation values to correct the imbalanced signals. The signal processing section calculates the difference value and uses it to adjust the output values of both PD pixels, ensuring that the corrected values reflect the true optical state. This feedback mechanism restores signal balance and enables accurate defocus amount determination despite saturation events.
2Measurement precision
If signal correction is performed after saturation occurs, then focus detection accuracy is maintained, but additional signal processing complexity is introduced
Solution Approach 1:
The patent reduces processing complexity by performing preliminary calculations of predicted output values using pre-stored light receiving angle characteristics and lens information. Rather than implementing complex real-time saturation detection and correction algorithms, the system pre-computes expected signal values and uses simple difference calculations to correct saturated signals. This approach maintains high focus detection accuracy while avoiding the need for elaborate correction mechanisms.
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 ensures accurate autofocus control by correcting output values and addressing signal imbalances, maintaining focus detection precision even with pixel saturation.
Implementation Method 1
photodiode split pixels each including a first photodiode pixel and a second photodiode pixel
Data Source
AI summary
Provided is an imaging apparatus including an imaging element that includes photodiode split pixels, the photodiode split pixels each including a first photodiode pixel and a second photodiode pixel, the first photodiode pixel and the second photodiode pixel outputting different pixel signals, respectively, a signal processing section that, in a case where output values of the pixel signals reach saturation values, performs a saturation handling process of correcting the output values according to the saturation values and predicted output values.