Image Sensor Phase Detection Excluding Defective Lines
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Solution Overview
Problem
Image capturing apparatuses face challenges in phase difference detection accuracy due to defective lines, which can lead to reduced yield and inaccurate focus detection, even when there are no defective lines in the captured image for viewing.
Innovation Solution
An image capturing apparatus and method that allows for separate signal reading from photoelectric conversion elements, generating a second signal using the image and first signals, and calculating focus lens movement based on phase difference without using signals from defective lines, thereby avoiding accuracy reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-dimensional detection area is used for phase difference detection, then the detection accuracy is improved, but the presence of defective lines causes deviation in results and reduces detection accuracy
Solution Approach 1:
The image sensor is divided into multiple independent line buffers, each capable of storing signal data from one line of pixels. This segmentation allows the system to process and evaluate each line independently, identifying and excluding defective lines while maintaining data from non-defective lines for phase difference detection calculations.
Solution Approach 2:
The system dynamically changes the parameter of line selection based on quality assessment. By evaluating signal quality metrics for each line and selectively choosing high-quality lines for detection calculations, the system adapts to varying line qualities and excludes defective lines from the detection process.
2Measurement precision
If two divided PDs per micro-lens are used for phase difference detection, then the detection capability is improved, but the read-out time is doubled
Solution Approach 1:
The readout operation is performed periodically and sequentially for different line groups. Instead of reading all pixels simultaneously, the system cycles through different line groups in periodic intervals, allowing parallel processing of multiple lines while maintaining the ability to read out divided PD signals efficiently.
Solution Approach 2:
Signal data from multiple lines are preliminarily stored in separate line buffers before processing. This preliminary storage action allows the system to prepare data from multiple lines in advance, enabling efficient batch processing and reducing the overall read-out time by avoiding sequential access delays.
3Measurement precision
If signals from all pixels are used for phase difference detection, then the detection accuracy is improved, but defective lines cause deviations and reduce accuracy
Solution Approach 1:
Defective lines are extracted and excluded from the detection calculation. The system identifies lines with abnormal signal characteristics and removes them from the set of lines used for phase difference detection, preventing them from causing deviations in the detection results while maintaining the use of valid line data.
Solution Approach 2:
The system implements feedback by evaluating the quality of each line's signal and using this evaluation to determine whether to include or exclude the line from detection calculations. This feedback mechanism ensures that only high-quality data contributes to the phase difference detection, maintaining accuracy while avoiding the负面影响 of defective lines.
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
Enables accurate phase difference detection without deviations and prevents yield reduction by excluding defective lines from the calculation, ensuring reliable focus detection in two-dimensional detection areas.
Implementation Method 1
an image sensor that includes a plurality of pixels, each including a plurality of photoelectric conversion elements
Data Source
AI summary
An image capturing apparatus comprises: an image sensor that includes a plurality of pixels, each including a plurality of photoelectric conversion elements; a readout unit that reads out a signal from a portion of the photoelectric conversion elements of each pixel as a first signal and reads out a sum of signals from the plurality of photoelectric conversion elements of each pixel as an image signal; a generation unit that generates a second signal for each pixel using the image signal and the first signal; and a calculation unit that calculates a moving amount of a focus lens for achieving an in-focus state based on a phase difference between the first signal and the second signal. The calculation unit performs the calculation without using a signal from a defective line.